Gold Bulletin 2000, 33(1) 11

Gold in Watchmaking

Lucien F TruebIn der Oberwis 9, CH-8123 Ebmatingen, Switzerland

Email: lucien.trueb@bluewin.ch

Received: 26 November 1999

The attractive colour of gold, its brightness, durability as well as its tarnish and corrosion resistance made itthe choice material for watch cases, from the earliest ‘onion’ of the 16th century to today’s multi-motorquartz wrist chronograph. But the use of gold was never just limited to the case and other visible parts. Firegilding was used in the earliest watches to protect baseplate, bridges and gears from tarnishing andcorrosion. In order to give the watch the highest possible value linked with aesthetics and functionality, most(but not all) watch parts have been made of gold alloys at one time or another or have been gold plated.Gold is purely functional as a brazing compound; it is indispensable for chip bonding, wiring and frequencyadjustment in electronic watches.

FROM TOWER CLOCKS TOPOCKET WATCHESIt is impossible to tell when time measurement devicesstarted to take advantage of the decorative andfunctional properties of gold. The precious metalcertainly was used in sundials, clepsydras andhourglasses of different civilizations many centuriesbefore the advent of clocks and watches. We do knowthat the first tower clocks were built in the last years ofthe 13th century and very early in the 14th, both inBritain and France. They quickly became statussymbols of churches, monasteries and castlesthroughout Europe all the way to Russia. It was onlynatural to coat the metal hand(s) and numerals withgold leaf, using the classical gold size as an adhesive, iea mixture of linseed oil and copals with finelypulverised ochre and litharge. Another possibility wasto fire gild them after rubbing with a mercury-goldamalgam; this technology can be traced back to the 4thcentury BC. Then as now, gold provided long termcorrosion protection and superb visibility.

The common view that tower clocks precededdomestic clocks is probably wrong, the developmentmay even have gone the other way. The first referenceto domestic timepieces indeed goes back to the end ofthe 13th century. Be it as it may, wall and table clockswere first commissioned or purchased by members ofroyal families, the nobility, high ranking clergy and thewell-to-do elite. Thus, the clock movement was more

often than not hidden in an exquisitely worked anddecorated case. All kinds of materials were used,including of course gold. Goldsmiths and jewellers(particularly in Paris and Geneva) were quick to realisethat the timepiece was a new product line for them.Only the very rich could afford solid gold, but therewas a substantial market for clocks made of gilt bronze,copper, silver or brass. Iron was preferred in Germany,it was copper plated by immersing it into a coppersulfate solution, then fire gilded.

At the beginning the 16th century, spring-driven,truly portable, drum shaped timepieces with just anhour hand appeared almost simultaneously in France,Germany, Great Britain and Northern Italy. Suchinstruments meant to be carried on the person werecalled watches. Their mechanisms were similar to thatof chamber clocks, but it had taken 50 years to achievethe required miniaturization, which was very labourintensive. Watch movements were expensive, suchluxury items thus deserved a gold case. The first goldwatches on record were owned by Queen Elizabeth I ofEngland (1533 – 1603); her inventory mentions thatthey were decorated with rubies, emeralds, pearls,garnets and agates.

From its earliest beginning, watchmaking was bothan art and a craft. This applied to the casemakers andto the makers of movements; the latter not onlysteadily improved timekeeping precision, but also tookgreat care in making their machinery look like worksof art. The pursuit of such beauty truly was “l’art pour

12 Gold Bulletin 2000, 33(1)

l’art”, as the movement normally was invisible to thewatch owner. It was not a passing folly: several Swissand a couple of German firms still (or again) make andsuccessfully sell watches with breathtakingly beautiful(and very expensive) mechanical movements. In formerdays, only the watchmaker would see them; nowadayssuch luxury watches are provided with a sapphire glassback, so the owner can enjoy the beauty he bought.This beauty is reduced to a network of golden lacesupporting barrel, gear train and regulating organswhen the movement is ‘skeletonized’. No dial isprovided in such watches; their movement issandwiched between two sapphire crystals in order tomake them as transparent and ‘airy’ as possible.

Aside from the above exceptions, the watchmovement is usually hidden from view; only the case,the dial and the other external parts are fully exposedto view. Early casemakers had to be superb artists, astheir clients belonged to the aristocracy and the verywealthy. Some of the greatest works of art ‘enminiature’ were created for them, particularly in Parisand Geneva – invariably using gold. The preciousmetal was not only exquisitely fashioned, engraved andpatterned, it also served as a base for diamonds, pearlsand coloured precious stones as well as for miniatureenamel painting. ‘Champlevé’ enamel was always donein gold, so was cloisonné, the motifs being drawn withgold wire glued to a gold substrate; firing the enamelalso welded the gold.

ART AND TECHNOLOGY

The beauty of the (mostly French and British) watches ofthe 16th and 17th century has never been matched.They were equipped with high quality movements onboth sides of the Channel, but they lacked ruggednessand durability in France. Miniature painting with metaloxides on a white enamel background fired on goldbecame a speciality of the craftsmen in Blois and Paris.They decorated the entire case and the dial in thismanner, the cover inside and outside, leaving only goldcircles and fine gold patterns at the periphery. Britishwatchmakers on the other hand fitted the best highprecision movements of the time into wonderfullydecorated cases using rock crystal, gold, silver, preciousstones and enamel during the Stuart period; some ofthose cases were imported from France. When luxury fellout of fashion under Cromwell in the middle of the 17thcentury, the very stark, oval shaped ‘Puritan watches’appeared; their case was usually made of polished brass,but plain polished gold was used occasionally.

With Huygen’s invention of the balance wheel andhairspring in 1675, the precision of watches gained anorder of magnitude. They now became instruments,not just beautiful pieces of jewellery giving theapproximate time. Gold – engraved and patterned –regained its place in the case; if the latter was made ofbrass, it was often covered with black leather orsharkskin, which itself was patterned with gold (orsilver) rivets. The movement, now a reason for prideand usually made of gilt brass, was provided with acircular, large diameter balance cock exquisitelydecorated with carved and engraved floral and animalmotifs; it entirely covered the balance wheel.

Inevitably, this led to excesses such as enamelledmedallions decorated with precious stones serving asbalance cock, engraved bottom plates and bridges,shaped pillars etc. Miniature enamel paintingcontinued though and still flourished until the end ofthe 19th century, both in Paris and Geneva. The sameapplies to unpainted, translucent enamel which wasapplied to gold watch cases with guilloché work; thistechnology was particularly appreciated in GreatBritain in the early 19th century. An earlier Britishspeciality in the middle of the 18th century was goldrelief (achieved by the repoussé technique) with mostlymythological scenes on both sides of the case.

The ‘problem’ of the French and Britishwatchmakers was that they catered for the rich: theyproduced individually crafted masterpieces in smallquantities at very high prices. The watchmakers in the

Figure 1 Gold blanks for cases and case bottoms. (Precinox, LaChaux-de-Fonds)

13Gold Bulletin 2000, 33(1)

Swiss Jura mountains and (to a lesser extent) inGeneva, applied the principles of mass production andextreme division of labour. This allowed theproduction of plain but functional timepieces atreasonable prices, which created a growing massmarket. The Swiss thus became aggressive competitorsof the British and French watch industries in the 18thcentury. First they undersold everybody with silverwatches for 20 francs and gold watches for 120 francs.Then they became technically innovative, as theirtechnology evolved from the verge to the cylinder andultimately to the anchor escapement.

As the fusée became unnecessary due to advancesin spring steel and spring technology, the watch couldbe made significantly thinner and smaller, whichmeant less gold for the case and still lower prices.Thus, the ‘onion’ of 1700 with a thickness of nearly 40mm and a diameter of 60 mm gave way to the 50 mm‘Lépines’ of 1780, which were only 15 mm thick.Another half century later, the craftsmen in the Valléede Joux were making movements that were just slightlyover 1 mm thick, which they fitted into 3 mm thickwatches. In order to beat their competitors, the Swiss

casemakers learned to make very thin gold cases whichwere rather weak, as they consisted of 0.15 mm goldplate and weighed only 20 to 30 grams. Thus, around1850, the gold in a British watch was worth 7 poundssterling, that in a Swiss watch only 2. Of course, thelatter was much cheaper, and it still was a gold watch,albeit quite delicate. This tradition of making goldwatches with an absolute minimum of precious metalcontinued with the advent of the wristwatch; oldtimers in La Chaux-de-Fonds vividly remember casesfor small ladies’ watches with a 6 3/4 line movementwhich weighed all of 1.6 grams.

THE GOLD WATCH INDUSTRY

In the latter part of the 19th and in the 20th century,the Swiss watch industry expanded enormously andbecame a dominating force world-wide. It alsosurvived many crises; the worst one in the early eightiesof the 20th century was due to the ‘quartz revolution’which swept away the entire branch of cheapmechanical watches. Some 60,000 jobs were lost in theprocess, which nearly corresponded to two thirds ofthe entire industry’s workforce. The well managedmanufacturers of high end watches hardly noticed thecrisis: there always is a class of very wealthy people whowill buy the ultimate in luxury, quality and beautyregardless of price.

Today, the Swiss watch industry keeps growingnicely in terms of sales even though the number ofwatches sold per year hardly changes at all. This meansthat the price tags are getting bigger, which can beeasily achieved by using more gold! This explains inpart why more than 90% of the world’s gold watchesare made in Switzerland. Some 450,000 pieces per yearbear the Swiss hallmark, more than a fifth of them areimported, mostly from Italy. The vast majority of goldwatch cases are 18 ct; only Britain, part of the BritishCommonwealth, the US and some Scandinaviancountries accept 14 ct gold watches and import 16 000of them per year, Japan makes even 9 ct cases for thosemarkets. The spread in terms of weight is very wide: 8grams suffice for a small lady’s watch, but about 65%of the Swiss gold watches bear the Rolex crown on thedial. Rolex cases weigh 40 g each, which has a verysignificant impact on the statistics.

Switzerland does not by any means have a totalmonopoly in the gold watch business. The three largeJapanese manufacturers of analogue watches (Citizen,Orient and Seiko) together produce some 25,000 goldcase watches mostly for the domestic market. Finally,

Figure 2 Cold impact die forging of a tonneau shaped goldcase. (Varin Etampage, Delémont)

14 Gold Bulletin 2000, 33(1)

Museum, La Chaux-de-Fonds the Indian watchmanufacturer Titan in Bangalore (a Tata Groupcompany) makes some 8,000 to 10,000 watches peryear with an 18 ct gold case weighing 40 to 60 g inthe men’s sizes. They are sold on the domestic andexport markets under the ‘Tanishq’ brand. All in all,gold watches world-wide absorb anywhere between 8and 12 metric tonnes of fine gold per year, dependingon whose statistics (or lack of them) you believe.About 15 Swiss companies produce gold watch cases,several of them also specialize in gold watch bands,which weigh between 20 and 100 g each. Thequantity of gold used for the latter purpose can onlybe roughly guessed at 10 to 13 tonnes; noquantitative information is available from themanufacturers, the biggest one again being Rolex.

The buyer of an 18 ct yellow gold watch has achoice of half a dozen colours plus another good halfdozen for white gold. There are distinct nationalpreferences: German 18 ct gold is bright yellow (‘2N’)and contains 10% copper and 15% silver, while theSwiss variety is a darker yellow (‘3N’) and contains12% copper and 13% silver. The latter colour ispreferred in combination with steel for ‘bicolore’ casesand bracelets. Rosé gold (‘4N’) contains 16% copperand 9% silver, while red gold (‘5N’) contains 21%copper and only 4% silver. Watchcases are mostlymade of the 2N type, as 95% of Swiss made goldwatches are exported. However, certain manufacturersinsist on rosé or red gold as their ‘trademark’ (4N and5N colours). The 2N and 3N type alloys are availablein fine grained varieties specifically for watchcases, as

they are easier to polish to a high gloss; traces ofiridium are added for grain growth inhibition.

As far as white gold is concerned, the 18 ct alloywith 16% palladium and 9% silver was quitewidespread in the days of cheap palladium. Nickelwhite gold has totally fallen out of favour because of itsallergenic potential. The law requires that no more than0.5 micrograms of nickel are given off per squarecentimetre per week; this is easily achieved, but nobodywants to take a chance. White gold is presently verymuch in fashion, but it is expensive, as the palladiumprice has enormously increased in the past few years.This is mostly due to the uncertain supply situation(70% of that metal comes from Russia) and steadilyincreasing demand for automotive catalytic converters.White gold alloys with 12.5% or just 10% palladium(the latter need manganese or iron for strengthening)have been developed to save palladium. Some of thenew white gold alloys can be hardened by heat treating,grain growth being inhibited with iridium. Other lowpalladium white gold alloys which do not need to berhodium plated were recently introduced.

The alloys Gold 990 (23.76 ct) with 1% titaniumand gold 986 (23.66 ct) with 1.4% titanium pluscopper, never made the breakthrough that had beenhoped for, despite their good mechanical propertiesand machinability. In the age-hardened condition, theyare similar to 18 ct alloys. For one thing, gold 990 and986 are about 30% more expensive than 18 ct gold, asthey contain a lot more precious metal. Also, one mustbe aware of the fact that any price differential at thelevel of the case is multiplied eightfold by the time thecomplete watch makes it into the retail store display.Furthermore, recycling this type of alloy posesproblems, both technical and economical, as goldrefiners are not used to dealing with titanium. Onlythe Japanese owned American-Swiss Waltham WatchCompany tried gold 990 in watch cases, but only withmoderate success; there were no followers.

SOLID GOLD WATCH PARTS

Gold watches can be immediately recognised if they areturned around: the back of the case must be made ofgold, while gold plated watches use a steel back.Professional burglars know that: they wouldn’t touch goldplate, for which there is no second hand market. Solidgold may be used in seven major parts of a modern wristwatch: case (including back and bezel), dial, hands,crown, pushers, bracelet and clasp (for leather straps).This applies to both mechanical and electronic watches.

Figure 3 The oldest coin watch on record: Florentine double ducathollowed out to fit a small, 1820 Lépine gold watch.(Girard Perregaux Museum, La Chaux-de-Fonds)

CasesThe invention of the wristwatch is claimed by severalcompanies, but it is likely that Girard-Perregaux in LaChaux-de-Fonds really were first. The GermanEmperor commissioned them as early as 1879 tofabricate a series of small watches equipped with aleather strap, as they were meant to be worn at thewrist by Naval officers. These watches were used asdeck watches for navigating on the high seas and hadto be corrosion resistant: for this reason, the cases weremade of 14 ct gold. Apparently, the very first wristwatches were gold watches; this seems to be ratherextravagant for armed forces issue, but stainless steeldid not exist yet and brass just would not do.

The Swiss watch case manufacturers buy most oftheir raw gold parts from two suppliers: Precinox in LaChaux-de-Fonds and Metalor in Neuchâtel. Both ofthose companies do their own chemical andelectrochemical refining to 99.99+ fine gold, whetherthey start from bullion or gold scrap, in order toeliminate impurities, particularly the hard osmium /iridium and/or ruthenium based particles, which makesmooth polishing impossible. This is followed byvacuum melting and alloying under vacuum. Precinoxalone have some 20 alloys in the 18 ct class forapplications in jewellery and watchmaking. Ingots arerolled to flat strips or bars, 8 – 10 passes are needed toachieve 75% reduction, then the material is annealed

to eliminate work hardening and rolling continuesfollowing the same procedure until the desired platethickness is reached. Bars may have a rathercomplicated cross section and are either used as such,drawn to wire (0.8 to 8 mm diameter) or processed totubing: such material is needed for making goldbracelet links, crowns, screws and other small parts.

Gold strips a few millimeters thick are the rawmaterial for the fabrication of watch cases. Flat, ringshaped parts roughly approximating the desired shape,including the horns for attaching the strap or bracelet,are cut out of the strips by blanking. This is as far asthe gold supplier normally goes; the next step isimpression die cold forging, using hardened, 1%carbon, manganese steel tools to give them the finalouter shape, which is mostly done by highly specialisedcompanies. Those tools are made by electro dischargemachining (EDM), using hand made or NC milledcopper prototypes of the future case as electrodes.Impression die forging is based on plastic deformation;it is an extremely demanding job which is masteredonly by highly specialised companies, Varin-Etampagein Delémont being one of the major ones.

The forging tools themselves and their inserts mustbe changed several times in the course of operations, asanywhere between 5 passes (for very simple shapes) upto 40 passes (for the most complicated cases) atpressures between 80 and 120 tonnes are needed forachieving the final shape. After every pass, the 18 ctgold pieces must be annealed at 640 to 650 °C in orderto soften them. Material is squeezed out of the edges(inside and out) at each pass in the press; this flash has

Gold Bulletin 2000, 33(1) 15

Figure 4 Albert Einstein’s Patek Philippe ultra-slim pocketwatch with gold case and engraved back, which hebought in 1915 after his move from Zurich to Berlin.(Patek Philippe Collection, Geneva)

Figure 5 “Tourbillon sous Trois Ponts d’Or” with threesymmetrical 18 ct red gold bridges. (GirardPerregaux)

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to be trimmed off several times in the course of forgingoperations. A precision of + 20 – 0 micrometers isroutinely achieved. Even though the sets of forgingtools are designed by computer, a tremendous amountof practical experience as to the flow characteristics ofgold under high pressure is stored in the programs.Impression die forging is particularly difficult with theasymmetric cases coming into fashion. It isadvantageous to polish the cases after each 4 or 5passes in the press.

Forging operations involve very expensive toolingbut give the case manufacturer nearly unlimitedpossibilities in terms of non-round shapes. Sharpinner angles (which occur in square, rectangular andtonneau cases) and deep grooves cannot be made bymilling at all. Furthermore, a forged piece has a near-perfect finish and can be polished or brushed withoutproblems. Forging closes any pore and microcracknear the surface, which is not the case with fullymilled objects. But innovations in terms of shape arenot possible before the forging tools have beenamortised. NC machines are much more flexible inthis respect; they are preferred for the fabrication ofsimple, round cases, on which the horns are brazed.The same applies for large, ring-shaped bezels, whichare often provided with a steel insert on the sidefacing the case in order to lighten them and savegold. The flat or slightly curved case bottom as wellas the bezel may be either blanked and forged, ormilled from a solid disk. The bottom is usuallystandardized in terms of size and thread, while theouter shape of case and bezel are often modified forthe sake of innovation.

The case manufacturers machine the inner recessesfor bezel, crystal, crown, movement and bottom,which involves milling, drilling, lathe cutting andtapping. Polishing is done by hand with mildlyabrasive pastes containing colloidal cerium oxide oraluminium oxide particles. This operation requires atremendous amount of know-how, skill andexperience; robotizing it is not economical, due to thesmall series. A perfect mirror finish is obtained bydiamond burnishing. The case manufacturercompletely assembles the case (including the crystal)and delivers it to the watch manufacturer, where thepre-assembled movement with dial, hands and crownis fitted. Finally, the strap or bracelet is attached.

In contrast with the rest of the Swiss watchindustry, the Swatch Group controls two fullyintegrated gold watch case and bracelet fabricationfacilities: Favre-Perret in La Chaux-de-Fonds andLascor in Sesto Calende at the South end of LagoMaggiore in Northern Italy. Both companies alsomake cases for high end watch manufacturers notbelonging to the Swatch Group. At the Lascor plant,fabrication starts with 999.9 bank bullion andinternally recycled fine gold to make the requiredstandard grade alloys (2N to 5N 18 ct gold alloys plusnickel-free palladium white gold not needing rhodiumplating), which are processed to strip or bar stock bycontinuous casting. Cases are made from stamped,forged, machined, diamond burnished and polishedgold strip. The bars serve as raw material for braceletlinks, which are made from forged pieces or wiredrawn tube sections. The nearly complete cases andbracelets are then brought across the border toSwitzerland where the composition is checked and theSwiss hallmark is stamped on. Then the cases arebrought back to Sesto Calende for final polishing andassembly. Recycling and chemical refining of the goldare also done in house by Lascor.

Aside from conventional watch cases, Lascormanufacture thin-walled, so-called ‘monocoque’ cases,mainly for the Tissot brand. Such watches are made forthe company incentive market in the Scandinaviancountries. The cases contain only 9.5 g gold for an 18ct men’s watch with a diameter of 32 to 33 mm; theyare cup shaped with integrated bottom, the movementis mounted from the top and must be removed inorder to exchange the battery.

The casemaking technology used by the Genevawatch manufacturer Patek Philippe lies halfwaybetween ‘big industry’ and handicraft. Patek is a truemanufacturer with a fully integrated production ofsome 25,000 luxury watches per year, 90% of which

Figure 6 The ‘Monnaie’ coin watch, based on an AmericanDouble Eagle. (Corum, La Chaux-de-Fonds)

have a gold case. There is one stainless steel modelfamily (for ladies) and small series of steel-gold andplatinum watches in the collection. Otherwise, thefirm identifies itself with gold and shows a definitepreference for pink (4N) and red (5N) 18 ct gold.Most watch models are available in three gold colours,in addition to palladium white gold.

As the series are too small for in-house gold refiningand alloying facilities, Patek Philippe buy pre-shapedcase rings (which always include horns for strapattachment), case bottoms and bezels as well as wire andforged links for metal bracelets from specialisedsuppliers. Thus, cold forged and even lathe cut pieces arereceived; they are finished at the Patek Philippe plant bycold forging using the final 5 to 8 dies followed by NCmilling, cutting and polishing. The idea is to buy asclose as possible to the final shape and generate only anabsolute minimum of scrap. Machining of the preciousmetal is done with dedicated machinery, even white andyellow gold scrap are separated at the source. Gold dustand filings are collected everywhere in the plant (partlyby permanently installed vacuum lines to the workbenches), melted and returned to the suppliers forrefining and re-alloying.

Patek Philippe is the last independent Geneva watchmanufacturer uniting all of the classical ‘professions’ ofwatchmaking under one roof and even trainingapprentices in all of them: designer, movement maker,goldsmith, jeweller, engraver, miniature enamel painterand chain maker. Thus, cases, bezels and bracelets aredecorated in Patek’s own workshops; this includessetting diamonds and coloured stones. Even the ancientart of engine-turning (‘guillochage’) has been revived byrevamping a vintage 1913 machine and having a longretired guillochage master train a new generation ofoperators. Engine turning is used mostly for patterningthe back and/or cover of pocket watches. This pattern isrecorded on a master plate and copied in reduced size bymechanically scanning the pattern, while the tool endwith a hard metal tip hammers on the gold. Miniatureenamel painting of cases is done to order, the theme isusually a classical painting which is copied “enminiature” on a matte gold background. The sameapplies to engraving of geometrical and floral patterns,which is entirely done by hand using simple steel tools.Very deep patterns are obtained by chiselling, whichactually involves the use of cold chisels and a mallet. Thewave-shaped ‘Geneva stripes’ are applied to themovement parts with a rotating boxwood tool.

While gold cases for many famous Swiss watchbrands are made by the thousands if not ten thousandsper year (add another zero for Rolex), a few small

manufacturers are doing quite well fabricating one-of-akind watches for wealthy collectors as well as smallseries of very special (and extremely expensive) pocketand wrist watches with all kinds of complications.Thus, Michel Parmigiani in Fleurier (whose companyshares are partly owned by the Sandoz Foundation ofBasel chemistry fame), makes a grand total of 800watches per year with some 40 employees. The casesfor those exquisite watches are either yellow, pink orwhite gold, with platinum thrown in for goodmeasure.

Most of Parmigianis cases are individually made bya superb craftsman and artist by the name of BrunoAffolter in La Chaux-de-Fonds who just recently addeda NC milling machine to his inventory of classical highprecision machinery, with which every piece used to behand crafted. Affolter literally lives in symbiosis withhis customers who just give him the dimensions of themovement they want to be cased with the instruction‘Do it my style’. The largest order he ever received wasfor 50 identical pieces, but the challenge heparticularly enjoys is the individual, very complicatedcollector’s piece, usually a pocket watch with repeater,perpetual calendar, ‘grande sonnerie’ or chronographfunctions. Waterproof gold cases for wristwatchrepeaters or Westminster chime watches are anotherspeciality of the house. Among his customers one findshigh prestige names such as Breguet, Girard-Perregaux,

Gold Bulletin 2000, 33(1) 17

Figure 7 Automatic skeleton wrist-watch with gold-platedmovement and 18 ct yellow gold case with fourquadrants engraving. (Parmigiani, Fleurier)

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Kelek, Ulysse-Nardin and Vacheron & Constantin.Parmigiani delivers the complete case, polished anddecorated including crystal, seals and crown.

A pocket watch case starts with a blanked, ring-shaped central part which is machined to the desiredshape by copying it from a brass model – or feedingthe appropriate software into the NC machine’smemory. Back, inner cover and bezel are made of coldforged or embossed gold plate; the hinges aremachined and brazed in place. Only very thin goldplate can be deformed by the repoussé technique,using appropriately shaped wooden tools; thistechnology is hardly used any more, as gold pocketwatches are luxury items which are expected tocontain a lot of gold. A Savonnette case made of 0.7to 0.8 mm thick 18 ct gold plate for a complicatedmovement weighs between 180 and 200 g (300 gbeing the extreme value), while an open face Lépinecase for a “Grande complication” weighs 150 g. Onthe other hand, only 75 g of 18 ct gold are needed foran extra flat pocket watch case.

Watch HandsAn analogue watch has at least a minute hand and anhour hand; a small or large (central) second hand is avery frequent feature, particularly in men´s watches.Thus, watch hands are usually sold by pairs or triplets,bearing in mind that a chronograph can have up toseven hands while complicated watches such as a“Grande complication” can have many more. Highlustre gold hands look very attractive, but in mostcases, gold plated brass is acceptable. Solid gold handsare only found in high prestige watch brands; Rolex,

the only luxury watch made in huge series, absorbs thelion’s share with several hundred thousand sets of goldhands per year.

The fabrication procedure of solid gold watchhands is practically identical to that of brass or goldplated brass hands. However, the series are muchsmaller; ten sets of a given style is not an unusualorder, 100 to 150 sets is considered as a large order,unless you make watch hands for Rolex. Only partsof the automated processing equipment for punching,patterning, embossing and cutting can be used. Thisis one of the reasons why gold watch hands are sovery expensive: no economy of scale, craftsmanshipinstead of automation. Add to that the often veryexclusive and complicated shapes required for theluxury watch trade: expensive tooling is then neededfor very small series. Diamond burnishing is used forvery high gloss gold hands. The ultimate, one-of-a-kind luxury watch is equipped with individually handcrafted gold hands; they look as perfect as if they hadbeen cut by an NC machine, but just a set of files wasneeded to fabricate them – aside from a tremendouslyskilled pair of hands.

Figure 8 Reverso ‘60ème’ with pink gold case and 14 ctbaseplate and bars. (Jaeger-LeCoultre, Le Sentier)

Figure 9 Automatic wristwatch with 18 ct yellow gold caseand 22 ct gold minirotor. Gold-plated gears andbalance wheel. (Patek Philippe, Geneva)

DialsThe watchface or dial is seldom made of solid gold.Shiny gold hands on a matte, finely engraved orpatterned gold watchface do not provide the world’sbest contrast, but they are tremendously elegant,particularly if both the hour-indexes and the hands arediamond burnished. Gold indexes (possibly in anothercolour than the dial), are machined individually; theyare provided with tiny feet which fit into 0.2 mmdiameter holes drilled in the dial; they are set by handand riveted in place. Since the watch dial is notsubjected to any appreciable mechanical stress, brittleblue and violet gold compositions (the intermetalliccompound AuAl2) are occasionally used for this part,notably by the Geneva manufacturer Patek Philippe.

The dial is the largest flat surface facing the watchowner; for this reason, nearly absolute perfection ismandatory. Any kind of finish has been used for watchdials: polished, matte, brushed, shot-peened,patterned, guilloché, engraved, enamel painted, foilgilded. Scales, numerals, brandnames, logos and anykind of pattern can be obtained by embossing andeven machining, but transfer stamping is not unusualeven on gold dials. The small second hand andchronograph counters often run in a circular, recessedpart of the dial, the angled edge of which is given ahigh gloss by diamond burnishing. Very special dials

are decorated by the cloisonné enamel technique ongold foils. The most expensive dials are of coursecovered with diamonds (‘pavé’); the support consists ofwhite gold which is drilled so the stones can be set, thealternative process being electroforming the fullypierced dial without machining.

As mentioned above, only luxury watches of thehighest standing are provided with a solid gold dial.Such dials may not look like gold at all, as they areoften rhodium plated or even titanium coated byPVD. Yet, the customer knows that he is looking at anexquisitely fashioned gold disk, the thickness of whichranges from 0.3 to 1 mm. It goes without saying thatthe time spent with fashioning and decorating such adial is worth much more than the precious metal itcontains. Besides, gold takes the absolute best guillochéor engraved finish. Solid gold is the preferred substratefor onyx, lapis lazuli or mother of pearl dials. It goeswithout saying that the two small disks representingthe moon in luxury moonphase indicators are alsosolid gold.

In watches with less than stratospheric prices, goldplated brass is almost the rule when a gold coloureddial is called for. The fabrication process is practicallythe same, regardless of the alloy: one starts with strips43 mm wide and 0.3 to 0.4 mm thick, which areprovided with guiding holes on both sides. They allowa precise positioning for the opening the central hole,the window(s) for the day and date indications andother holes (small second hand, chronograph counters,etc.) by punching. The holes for the index feet aredrilled, due to their small diameter. Then, the futuredial is cut out of the strip by blanking between theappropriate punch and die.

The rough disks are ground to perfect planarityand polished. Recesses are milled in, patterns may beapplied before the dials are run through a series ofcleaning and washing baths (only aqueous detergentsolutions and pure alcohol are permitted nowadays).Rotating copper brushes are used for brushing. Golddials may be given a flash of 24 ct gold byelectroplating to adjust the colour; the same applies tobrass dials which need only a 0.3 micron gold coatingas there is absolutely no wear on this part of the watch.

Galvanoformed dials are a speciality of the BlöschCompany in Grenchen, Switzerland: this technology isused when complicated patterns are needed. One startswith a mould bearing the desired pattern, from whichany desired number of polystyrene replicas can bemade. Vacuum evaporation of silver makes themelectrically conductive. Copper is then electroplated tothe desired thickness (0.3 to 1 mm) and ground to

Gold Bulletin 2000, 33(1) 19

Figure 10 Skeleton 18 ct movement by Frédéric Piguet in aSapphire watch case. (Century Time Gems, Nidau)

20 Gold Bulletin 2000, 33(1)

perfect flatness. Finally, the plastic substrate is removedwith a solvent: one is left with a silver plated copperdial, which can be galvanically gold plated,photolithographically masked and further patterned(eg with black nickel) for multicolour dials.

Crowns and Pushers Quartz and automatic watches do not of course needto be wound, but they have to be set and the date mustbe adjusted once in a while (unless you have aperpetual calendar). The crown is thus functionallyindispensable in any kind of watch, but it also has animportant aesthetic function. Just changing the style ofthe crown can make the watch look quite different.The same applies for chronograph pushers andaccessory pushers, but the styling latitude is not verywide with those elements: they can either be round orflat. In truly waterproof watches, both crown andpushers are of the screw-down type. One of the main,fully integrated manufacturers of steel, titanium andgold crowns in Switzerland is Meco in Grenchen. Itbelongs to the Swatch Group, but sells about 40% ofits production to manufacturers of luxury watchesoutside the group.

Gold crowns and pushers are a must for solid goldwatches; they cost up to 4 to 10 US$ a piece eventhough they weigh only 0.25 to 0.5 g. They are madefrom round or flattened 18 ct rods, respectively, whichare cut in sections and given their outer shape (andlogo) by impression die cold forging, with usually justtwo passes followed by washing, polishing, annealingand some lathe cutting. Remarkably, the volume of theraw gold cylinder is calculated so accurately thatabsolutely no flash is formed during the forging

operations. No polishing is required after cold forgingeither, as the dies are made to exacting specifications;crowns requiring a mirror-type finish are diamondburnished. Watches with gold plated cases are fittedwith electroplated stainless steel crowns, which arefabricated just like solid gold crowns.

Simple crowns which are just tapped so they canbe screwed on the winding stem are (almost) a thing ofthe past. Nowadays, even inexpensive watches are atleast water protected, which means that the windingstem passes through a short piece of pipe (‘tube’)brazed to the case or given a press fit. For waterprotection, the crown is hollowed out and the innerwall is grooved on a high precision lathe. It can then befitted with two tiny neoprene O-ring gaskets whichslide on the tube wall when the crown is pulled.

Truly waterproof watches are equipped with screw-down crown(s) and chronograph pushers. Most ownersof such watches do not realise that their watch crown isnot just tapped, but is hollowed out extensively inorder to make room for a sophisticated mechanismconsisting of at least seven and up to a dozen tiny, highprecision, moving metal parts which are made bymilling, drilling, tapping and turning on automaticNC machines. They must be assembled manually andfitted into the crown with several gaskets by personnelwith the skill of a watchmaker. They have the functionof a position selective clutch which disengages thewinding stem from the crown in the lowest position,so the crown can be freely screwed onto the tube. Atthe same time, unscrewing the winding stem from themovement must be avoided. Waterproofing ismaintained regardless of the position of the windingstem.

Gold Movement PartsGold may be used for most parts of a mechanicalwatch movement, but gold plated brass looks just thesame and is much cheaper. Yet, automatic (ie selfwinding) movements for high end watches areprovided with a gold rotor. In order to achieve thehighest possible density, a 22 ct alloy is often chosenfor this part. Mechanical movements of the luxuryclass sport gold “chatons”, ie brightly polished goldrings for setting the stones, which otherwise are justpress-fitted into the brass baseplate and bars (‘bridges’).Stones set in a chaton can be replaced (which is not thecase otherwise), but this type of repair is very rare.Chatons are held in place with tiny steel screws andprovide a pleasing colour contrast with rhodium platedor German silver main plate and bridges, dark red rubybearings and blued screwheads.

Figure 11 A two ounce fine gold bank bullion bar, hollowedout to serve as a watchcase. (Century Time Gems,Nidau)

Gold alloys of the 14 ct or 18 ct type are perfectlysuitable for fabricating the basic parts of a movement,ie baseplate and bars for particularly valuable watches.Even though the mechanical characteristics of thosealloys are quite adequate for machining, rolling to thedesired thickness is quite difficult, as gold tends torebound and creep; such effects can only be partlycompensated by heat treatments, milling and grinding.Among watchmakers, gold has a reputation of being a‘temperamental’, ‘nervous’ metal.

Watch movement gears and non-lubricated scapewheels have often been made of gold, eg by the classicalDanish watchmaker Urban Jürgensen for whom thepreferred alloy was 9 to 10 ct; it is harder than brass anddoes not significantly wear in contact with the steelpinions and under the effect of the “hammering” by theanchor pallets. Craftsmen in the Vallée de la Sagne wereeven specialised in gold gears and gold screws in the19th century, this is where Jürgensen bought thoseparts. The rationale was mostly aesthetics, as solid goldcan be polished to a mirror finish much superior towhat can be achieved by plating. The new coaxialescapement developed by George Daniels on the Isle onMan and commercially produced by Omega since 1999started with a prototype scape wheel made of gold. Andof course the dart at the upper end of the pallets fork issometimes made of gold instead of stainless steel, againto avoid lubrication.

Hairsprings made of gold-copper (sometimes gold-silver) alloys with 75% to 87.5% Au were used byBreguet in clocks and also by the manufacturers ofmovements for high quality British watches of the 19thcentury, bearing famous names such as Edward J Dentand John Roger Arnold. Such hairsprings were stronglywork-hardened by cold rolling; they did not corrodeand were nonmagnetic, but they were temperaturesensitive. They had to be combined with bimetallic,temperature compensated balance wheels. Pocketwatch movements with a gold hairspring were actuallyimported from Le Locle and just cased in Britain. JohnArnold, Thomas Mudge and Thomas Earnshaw as wellas Ulysse Nardin in Le Locle used gold hairsprings intheir famous marine chronometers. Gold waseventually replaced by Invar type nickel-iron alloys,after much experimenting with other exotic,nonmagnetic materials such as platinum and evenglass. Elastic gold later found a small niche in the‘Palliney’ suspension alloys, which were used to makethe torsion spring in the now almost defunctelectromechanical measuring instruments. They weretried for hairsprings in the forties, but could notcompete with the much superior Invar type alloys.

Watch movements of the highest quality grade madeby Lange & Söhne in Glashütte near Dresden wereroutinely equipped with a gold anchor and a gold scapewheel (presumably, a 14 ct alloy was used) well into the20th century. A gold anchor and scape wheel provideperfect corrosion protection and are non-magnetic, butthey do not make much sense mechanically, as theyshould be as light as possible. Gold plating the balance iscurrent practice, but this is not the case with the anchorwhich nowadays is almost invariably made of steel.

A watch bearing alloy typically consisting of 37.5%Au, 27.1% Cu, 22.9% Ag and 12.5% Pd was stillquoted in the literature towards the end of the 19thcentury, but it could not compete against rubywatchstones. The latter were invented by the Geneva-born mathematician and astronomer Thomas Fatio in1704 and came into routine use in English watchmovements in the first third of the 18th century.

To the author’s knowledge, the mainspring, thebalance, the axles, the pinions and the winding/settingmechanism seem to be the only metal parts of amechanical watch that have not at one time or anotherbeen made of a gold alloy. A watch fully made of goldalloys is a challenge still waiting for a skilfulmetallurgist cum watchmaker.

REMARKABLE GOLD WATCHES

Constant Girard-Perregaux, the founder of the presentGirard-Perregaux company, was extremely fond ofgold, his favourite being the 18 ct pink gold (with20.5% copper and 4.5% silver). He used it not onlyfor the case, dial, hands and crown, but also for watchmovement parts such as bars, balance wheel counterweights, non-lubricated pallets wheel and detent spring(he was using a variant of the detent or chronometerescapement). This gold alloy can be heat treated at 280°C and hardens to 320 HV, which is close to thehardness of brass. Other manufacturers have used pink14 ct gold for the detent escapement parts.

After thirty years of experimenting, Girard-Perregaux hit upon the design of his masterpiecearound 1880. It was the “tourbillon sous trois pontsd’or” in which three identical, symmetrically placedbar shaped pink gold bridges support the tourbillon,the barrel and the concentric axles of the minute andhour hands. Only about thirty watches of this uniquedesign were built in Girard-Perregaux lifetime. But theoriginal pocket size model was recreated in 1982 andminiaturized to wristwatch size a few years ago; it hasbecome the leading model of the collection.

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22 Gold Bulletin 2000, 33(1)

Frédéric Piguet in Le Brassus (a Swatch Groupcompany in the Vallée de Joux specializing in finemechanical movements), have a 9 line mechanicalmovement (‘Calibre 21’) with 18 ct gold bottomplateand bridges in their catalogue. This movement isparticularly attractive when it is skeletonized in orderto make it as transparent as possible. Jaeger-LeCoultre,in nearby Le Sentier, issued a special series of theirfamous ‘Reverso’ in 1991 to celebrate the 60thanniversary of this model. It had been originallydesigned for British Army officers in India, who oftenbroke their watch crystal while playing polo. Flippingthe case around in its sophisticated metal supportsolved that problem. The commemorative model had apink 18 ct gold case (20.5% copper and 4.5% silver)and a ‘gold movement’, the baseplate and the four barsbeing made of 14 ct gold.

The ultimate gold watch case was designed in theseventies by Hans Ulrich Klingenberg, founder of theCentury Time Gems Company in Bienne (now innearby Nidau). The case consisted of a standard finegold bar (1 troy ounce 999.9 gold for the ladies model,2 ounces for gentlemen). Of course it had to bemachined to accommodate the movement and thewinding stem, but this weight loss was compensated bythe weight of the bezel and the attachments for thestrap. There was no dial, but the bullion used wasminted to a high gloss; the fineness indication andserial number being left unchanged in most models.The sapphire crystal was pressed against the gasket bythe bezel, 18 ct gold screws were used for assembly. Akind of bullion watch was also made by Corum in LaChaux-de-Fonds in the eighties, using brightly minted15 gram gold bars for the watchface; 10, 5 or even 2.5gram bars were sufficient for the smaller ladies’ models.

Another very direct way of showing off gold is thecoin watch. This is a traditional item, as there is a golddoubloon watch dating back to 1820 in the GirardPerregaux collection in La Chaux-de-Fonds. However,the hollowed out coin just acted as an outer case for atiny Lépine gold watch which can be freely taken out.The baseplate, the bars and the dial of this watch areall made of solid gold. Modern coin watches with anintegrated movement were launched by Corum in LaChaux-de-Fonds in 1964 and are still made today. Tothis effect, a real gold coin is split and machined inorder to accommodate a super slim quartz ormechanical movement. The American Double Eagle ($20 for men) and the $10, $5 and $2.5 Eagles forwomen are most popular, followed by the FrenchNapoleon, the British Sovereign and others. Once it isprovided with its movement and crown, the coin is set

in a slender gold ring with discrete indexes andattachments for the strap. This ring also acts as a bezelfor holding the sapphire crystal.

GOLD PLATING

It was already mentioned that leaf gilding and firegilding have been used since the very beginning ofclock and watchmaking. Those technologies werealmost completely replaced by electroplating, whichwas invented in 1802 by Luigi Brugnatelli, a professorof chemistry at the university of Padua. Brugnatelliused an early version of Volta’s pile, the very firstbattery. He succeeded as early as 1805 to gold platesilver coins, but it took 40 years to develop the processfor industrial use. It was patented in 1842 by HenryFox Talbot.

The watch industry is a big user of electroplatedgold: cases, bracelets, hands, bezels, dials, crowns andpushers can be made of stainless steel (the 316 Lvariety is usually chosen), brass or even ‘alloy’ (a zincalloy containing aluminium, copper and magnesium)and then gold-plated. The thickness of this platingvaries tremendously (it is of course directly related toprice), ranging from a 0.1 micron flash on goldcoloured titanium nitride to anywhere between 3 and15 micron electroplated 18 ct gold.

As to movement components, brass baseplates andbridges are given a 3 to 5 micrometer gold plating ontop of a 1 to 3 micrometer nickel base for corrosionprotection and decoration (the alternatives are plainnickel for cheap watches, rhodium for expensive ones);this of course applies both to mechanical andelectronic movements. Brass gears (almost invariablyengaging a hardened steel pinion) are given a similargold plating, but before cutting the teeth. Soft goldwears off onto the hardened steel and builds up asticky black trace which can slow down or even stopthe movement.

There is practically no more gold plating of brassand alloy cases in the Swiss watch industry, as such lowend items are exclusively made in the Far East. Butgalvanic gold plating of high quality stainless steelwatchcases still has its importance, even though yellowmetal has recently fallen out of favour. Every plater hashis own favourite recipes and procedures for achievinghigh gloss, low porosity gold coatings on stainless steel,but most galvanic baths are based on gold chloride,sodium hydrophosphate, sodium sulfite and potassiumcyanide. Zinc and copper salts are added in order toobtain wear resistant, 18 ct coatings. The temperature

usually is between 50 and 80 °C, the voltage is 1.5 V atlow current densities. The positive electrode is made ofplatinum plated titanium.

A full cycle of 7 to 12 micrometer plating andrinsing of steel watchcases takes 3 to 4 hours. A 12micrometer plating for example usually consists ofthree different coatings. The first 2 micrometers on thestainless steel substrate consist of very pure 23.5 ct goldwith cobalt. The main, 9 micrometer thick coating is18 ct gold with zinc and copper, while the abrasionresistant top coating consists of high carat gold withnickel and indium. The composition is adjusted tomatch the colour of other visible watch parts, such asface, hands, crown and bracelet.

Thermally evaporated gold is found on thesapphire crystal of some high end watches in the formof discrete lines or patterns, which of course are onlyapplied near the edge. More particularly, this kind ofdecoration is used by the Rado company. The entirecrystal is sometimes given a warm tint by goldevaporation: dial and hands are then seen through agold film. Furthermore, golden logos, indexes andnumerals can be vacuum-evaporated on the innersurface of the crystal.

GOLD IN QUARTZ WATCHES

The electronics industry is the second largest user ofgold (after the jewellery trade), as it consumes morethan 200 tonnes of gold per year world-wide. The inertnature, high electrical conductivity and low contactresistance are the most appreciated properties of goldin electronic applications. The electronic componentsused in quartz watches are highly specialised, but theydo not in principle differ from the ones used in othermicroelectronic applications. Thus, all quartz watchesare equipped with a tuning-fork shaped quartz crystalgenerating the frequency of 32 768 Hz. The latter isdivided down to 1 Hz by the CMOS integrated circuit(often a microprocessor) and is used to control either astep motor in analogue watches, or a liquid crystaldisplay in the digital variety. The latter has nomechanically moving parts (aside from pushers neededto adjust the time and trigger special functions).

In analogue quartz watches, the step motoractuates the second hand, which transfers its motionvia a gear train to the minute and hour hands. Thebasic construction of this type of watch is very similarto that of the mechanical watch, except that the poweris provided by a silver oxide-zinc battery (or a smallrotor-generator, a set of solar cells or a thermoelectric

generator in conjunction with a super-cap or arechargeable lithium ion battery); the regulating organsare of course replaced by the quartz crystal. Thesimilarity even goes a step further in the high endchronographs, in which the timing functions arepurely mechanical, but operate in conjunction with ananalogue quartz movement for accurate timekeeping.The use of gold (mostly plated) in such watches is nodifferent than in classical mechanical timepieces.

As mentioned above, gold finds many uses in thespecifically electronic parts of quartz watches. As puregold is ductile, soft and readily forms cold welds, goldand gold plated components can be joined bythermocompression bonding. The bonding wiresconnecting the silicon chip of the integrated circuit tothe lead-frame are usually made of gold; only 10% ofthe ICs use aluminium or palladium bonding wires.Wire in the diameter range of 13-37 micrometers isused, the average being 25 micrometers; it is producedby standard multiple set drawing through diamonddies. Gold for this application is doped with traces ofaluminium, beryllium and calcium, or more recentlyrare earth metals which are added to 99.999 gold toinhibit grain growth and recrystallization.

IC connectors consist of bronze electroplated withgold; 0.1 to 1% of Ni or Co are co-precipitated toincrease the hardness from 60 HV to 150 HV. Thesame applies to the contact lugs for the battery. Watchbatteries of the silver oxide zinc type consist of alaminated nickel-steel-copper cover in contact with thezinc powder anode (with up to 1% mercury) and asteel bottom part filled with silver oxide acting ascathode. Both materials are pressed to porous, pillshaped bodies and impregnated with a potassiumhydroxide electrolyte. The inside surface of the cover incontact with the zinc powder consists of copper for ahigh hydrogen overvoltage and minimum hydrogengassing. In former days, the copper film was given agalvanically deposited, 0.2 to 0.4 micrometer thickgold flash in order to further suppress hydrogengeneration at the zinc-copper interface. However, goldin watch battery covers became unnecessary in theeighties, as the hydrogen overpotential can becontrolled by using very pure zinc, while the toxicmercury in the zinc anode is (at least partly) replacedby indium.

Printed circuit board (PCB) tracks are plated withgold to avoid corrosion of the underlying copper and toimprove solderability. The quartz crystals generating thefrequency of 32 768 Hz also contain gold: the preciousmetal evaporated on both sides of the tuning-fork formscomplex patterns of contacts and gold patches which

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24 Gold Bulletin 2000, 33(1)

lower the resonant frequency. The latter is automaticallyadjusted to the correct value by computer-controlledlaser beam evaporation before encapsulation.

A really exotic use of gold in an electronicmovement is found in the luxury quartz watches ofGirard-Perregaux in La Chaux-de-Fonds, where thebattery is hidden unter a corrosion proof solid goldcover – decorated with Geneva stripes, just like thegold plated baseplate.

FUNCTIONAL GOLD

The aesthetic and functional aspects of solid gold (andplated gold) are intertwined in all the watch partsreviewed so far. However, there are importantapplications where gold is used, even though it remainstotally invisible. For example, gold has a purelyfunctional role in the new, glossy black and very hardDLC coatings (diamond like carbon) on cases, braceletlinks and dials. DLC is deposited on gold plated brassat 450 °C; the galvanic gold coating acts as a diffusionbarrier for the zinc in the brass. This technology can becombined with selective lift-off. For example, thenumerals on a dial are generated by using the classicalphotolithographic technique. Copper is plated on thegold wherever it is not protected by the photoresist.After removal of the latter, the entire dial is coated with1 micrometer of DLC. As this coating is porous, anacid treatment dissolves the copper under the DLCwhich is lifted off in the process. Gold numeralssurrounded by black DLC are the end result.

Another functional use of gold is found in thebrazing of stainless steel watchband components. Agalvanic gold-nickel coating acts as a perfect, flux-freesolder, ie a gold-nickel eutectic with a melting point of950°C. This eutectic flows into the recesses bycapillarity, exposed parts of the surface have the colourof stainless steel. Gold-copper-tin and gold-tineutectics were developed for brazing gold attemperatures as low as 280°C.

ACKNOWLEDGEMENTS

The author thanks the following persons for their kindco-operation: Bruno Affolter (Succ. Marcel Robert, LaChaux-de-Fonds); Roland Aubert (Frédéric Piguet SA,Le Brassus); Jürg Brunner and Marc Gilgen (CenturyTime Gems Ltd., Nidau), Catherine Cardinal (MuséeInternational d’Horlogerie, La Chaux-de-Fonds),Pierre-Olivier Chave (Precinox SA, La Chaux-de-Fonds); Yves Droz (Musée de la Montre, Villers-le-Lac), Benoit Conrath and Michel Parmigiani (PMAT,Fleurier); Anne Kretz and Jasmina Steele (PatekPhilippe, Genève), Alain Munier (Varinor, Delémont);Jack Ogden (National Association of Goldsmiths,London); Simone Prévalet (Jaeger-LeCoultre SA, LeSentier); Christian Raub (Schwäbisch-Gmünd);Claude Roulet (Corum, Ries Bannwart & Co, LaChaux-de-Fonds); Paul Rüetschi (Grandevent), SylvieRumo and Willy Schweizer (Girard-Perregaux SA, LaChaux-de-Fonds), Peter Röthlisberger (MECO SA,Grenchen); Clayton O. Ruud (Pennsylvania StateUniversity); Willi Salathé (Swatch Group, Biel);Maurizio Schiavo (LASCOR SpA, Sesto Calende);Kurt Schindler (W. Blösch AG, Grenchen).

ABOUT THE AUTHOR

The author is a graduate of the Physical ChemistryDepartment of the Swiss Federal Institute ofTechnology (ETH) in Zurich, Switzerland. He workedas a research metallurgist and materials scientist bothin Switzerland and the United States. From 1972 to1997 he was the science and technology editor of NeueZürcher Zeitung, the leading daily newspaper inSwitzerland. He is the author of numerous articles andtwo books on gold and watchmaking, respectively. Heis currently active as a freelance science writer andbook author.