Professional Diploma in Jewellery Design Magics of Metallurgy

Professional Diploma in Jewellery Design

Magics of Metallurgy Module 1 Lesson 7

Summary Notes

2 www.shawacademy.com

PROFESSIONAL DIPLOMA IN JEWELLERY DESIGN

Contents

3 Lesson outcomes

3 Introduction

3 Introduction to metallurgy

5 Platinum Groups Metals

8 Gold and silver

13 References



Introduction A jewellery designer is like a painter, except we paint our canvas with precious metal, combining different techniques with

specific tools and decorate with gemstones, enamel, resin, and a variety of alternative materials. Just like a painter needs

to learn the properties of different paint, the psychology of colour and the effects of different brushes, a jewellery designer

must understand the properties, characteristics, and capabilities of precious metal to fully embrace their passion and

reach optimal creative design solutions.

Precious metals have such unique characteristics and have a permanence throughout time. There is an intimacy that

exists when we yield raw treasures from the earth and transform them into cherished heirlooms.

Before we jump into the wonderland of metal, I would like you to think of the first time you saw a jewellery piece. Can you

remember it? I remember it clear as day. My mother has a yellow gold bridal set. And from a young age, I was completely

mesmerised by the colour and fascinated with how it was made.

Introduction to metallurgy Metallurgy is the scientific investigation into crystalline behaviours, the effects and uses of the different metals.

In 1864 a microscope was used for the first time to study the characteristics of steel. This event gave birth to the science of

metallurgy. By 1925 x-rays and wave mechanics were used to extending the understanding of metals.

Preciousness There are many aspects to determine the preciousness of metal: The rarity, economic value, and demand. However, there

are a few additional factors to consider creating precious jewellery. But before we start, what is the first thing you think of

when I say the word “precious”?

Who just thought of Smeagal/Golum saying ‘My precious’? I hope there are some Lord of the Rings fans in my class.

Lesson outcomes By the end of this lesson, you should be able to:

• Explore metallurgy

• Explore preciousness of metals

• Introduce metal alloys

• Identify the properties of precious metals

• Explore basic manufacture skills and techniques

Practical lesson outcome:

Comprehensive knowledge of precious metals and their properties, characteristics and uses.



Precious jewellery

The lure and infatuation with precious jewels dating back to an estimated 3000 BC. Jewellery made with precious metals

plays an important role in people’s lives as a meaningful ornament to be worn. It is a magical fetish that represents

something different to every person, but mostly it attests to love, loyalty and friendships. Precious jewellery celebrates

some of the most cherished moments in our lives.

To create precious jewellery

We must consider the technical skills required to create precious jewellery. Therefore, the basic understanding of metals is

imperative in the design and manufacturing process of jewellery. Before you can run, you must first learn to walk. Precious

jewellery must have unique qualities, making it near impossible to replicate.

It is trivia time!!

Do you know what is the most common metal found on earth? I hope you did not think it is one of the precious metals!

That was a test to see if you remembered the introduction to precious metals in lesson 2!

The most common metal found on earth is iron as a large portion of the Earth is made of iron. And the most common

metal found in the earth’s crust is aluminium. These are both non-precious metals.

What is metal?

We all know what metals look like, but do you know what metal is? Metals are made of clustered atoms. Metal has a

crystalline structure arranged in a regular, geometric pattern. The most important concern in jewellery is the behaviour of

these structures.

Metal & alloys To understand metal, we must learn the behaviour of their structures. This is where it gets very technical. To design or

work with precious metals, we must first understand alloys.

Alloy! Alloy!

Which of the below definitions are true?

A. An alloy is a blend of two metals

B. An alloy used to mine metals

C. An alloy is a blend of metal and/or elements

The answer is C: It is a common misconception that an alloy is only a blend of two metals. An alloy is a blend of metal

and/or elements. Well done if you knew this one!

What is alloy?

Let us quickly refine what alloy means:

An alloy is a metal that has been combined with other substances to achieve specific desired properties. Example of these

properties includes making it more malleable, harder, or stronger.

Metal alloys

To change the properties and capabilities of precious metals, pure metals gets mixed with other substances. This process

is called alloy.

If you have a pure metal, you have one kind of atom. If you add an alloy, you have two or more elements that are

combined.

This changes the properties of the metal.



Wait. What? My jewellery is not pure??

Sorry to break it to you, but no, unfortunately, it is not 100% pure. If you are wearing any jewellery, have a look for the

metal hallmark. Your jewellery will have a hallmark to indicate the purity out of 1000.

For example: if your gold jewellery is hallmarked 750, it is 75% pure gold (also known as 18 karats).

Malleability So, we just talked about metal alloys to make the metal more malleable. Did you know what the term meant?

Malleability… Is that the ability to mall?

Because then I have my masters in malleability! No, it is not the ability to mall.

Malleability

Malleability is the ability to deform and forge metal due to their crystal structure. When stress is applied, the crystals slide

over each other. Each metal has a lattice system; a more symmetrical crystal is easier to deform.

Form follows function

Forging and forming into desired shapes is possible thanks to the malleability of precious metals. Example of techniques

used includes hammering, bending, chasing and repoussé.

Lattice have a good time

The precious metal has a face-centred cubic lattice system. This means that the crystal structure consists of atoms

arranged in a cube. And this enables easy movement in three directions. So, you can have a good time when forging and

forming!

If you had to guess, which metal do you think is the most malleable?

A. Platinum

B. Gold

C. Silver

The answer is B – Gold. A single ounce of gold can be forged roughly into a flat sheet 5 meters on a side and can be as thin

as 0,000127mm or 400 times thinner than a human hair. Gold star if you got that right.

Platinum group metals (PGM) We will start with the platinum metal group. What is the first thing that comes to mind when I say Platinum?

Who else thought of platinum as the music recording certification? This certification was introduced in 1976 for the sale of

1 million albums and 2 million for singles. How amazing would that feel?!

Platinum Platinum is the most sought-after metal of the precious metal group. So, what makes it so superior?

Properties of platinum

• Atomic number: 78

• Atomic symbol: Pt

• Atomic weight: 195.08amu

• Melting temperature: 1773°C

• Specific gravity: 21.45g per cm³

• Hardness: 4 – 4.5



You do not have platinum? What a Pt!

Characteristics of platinum

Platinum has 5 characteristics that makes it so special:

Platinum is resilient:

• Exceptionally resistant to tarnish and corrosion - which means it does not oxidize and is unaffected by common

acids

• With a density of 21,45g per cubic cm, platinum is more durable than the other metals used for jewellery

• Important to mention that due to its density, platinum takes much longer than gold to polish

Platinum’s rarity:

• Platinum is an extremely rare occurrence in nature, and only found in a few places on earth

• If you would like to know how rare platinum is… Annually, the production of gold (about 2600 tons) is nearly 14

times higher than platinum (about 160 tons)

• The complex process of platinum mining also contributes to the high value

Platinum’s malleability:

• Make it very easy to shape, form and forge

• Pure platinum can be rolled into wire 0,001mm in diameter

• Its malleability makes it ideal for settings as it can easily bend and shape to set stones without springing back

• Best metal for tension settings

Platinum’s purity:

• Platinum jewellery is manufactured at a fineness of 95% pure platinum

• This purity increases the gentleness on the skin and is hypoallergenic

• Platinum will not lose its lustre or colour

Timeless:

• Platinum is distinguished as being a timeless metal that will stand the test of time, making it the ideal metal

choice for heirlooms.

Uses of platinum

Platinum is truly a magical metal as it has so many uses:

• Its distinctive characteristics makes it exceptionally ideal for jewellery

• It can be used in catalytic converters, but due to its high value, palladium is used instead

• Its inertness also makes it suitable for dental fillings, surgical tools, and laboratory apparatus

• Lastly, platinum is also used in the electrical industry, in lasers and the make of photography materials

Palladium

Palladium is part of the platinum group metals; however, it is not as widely known as platinum. Due to sharing very similar

characteristics, palladium is used as a substitute for platinum jewellery.

First, do you know where the word “Palladium” comes from? Is it:

A. Pallas

B. Pallads

C. Padium



The answer is A – Pallas.

Palladium is named after the asteroid Pallas. Fun fact: Athena the goddess of Wisdom is also referred to as Pallas.

Properties of palladium


• Atomic symbol: Pd



• Specific gravity: 12g per cm³

• Hardness: 4 – 4.5

What did the gambler do with his cards? He palladium!

Characteristics of palladium

The characteristics of palladium are very similar to that of platinum:

• Resilience – Palladium does not tarnish or lose its natural white colour and therefore it does not require rhodium

plating, however, both surfaces will show wear over time, so it only requires cleaning and polishing

• Rarity – Along with platinum, palladium is one of the rarest precious metals

• Weight – Palladium is a lot lighter than platinum, similar in weight to 14k gold, but palladium is more durable than

white gold

• Purity – 95% pure palladium with 5% ruthenium and/or iridium

• Palladium is also hypoallergenic.

Who is up for a quiz? Who can remember which famous movie was palladium used?

Iron man!

• Iron Man got his power from the ‘arc reactor’ in his chest

• The superhero was slowly being poisoned because of the palladium in the ‘arc reactor’

• This is based on facts: Palladium can be toxic to the body

Uses of palladium

• Jewellery - The malleability of palladium and its resistance to tarnish makes it a very popular metal for jewellery

• Catalytic converters - The most common use of palladium remains to be used in catalytic converters instead of

platinum

• Store and filter hydrogen - Palladium can absorb up to 900 time its volume of hydrogen and heated palladium can

easily diffuse hydrogen, making it suitable to purify hydrogen

• Electrical appliances – Palladium is used to coat electrodes of multilayer ceramic capacitors (for example laptops

and cell phones)

• Surgical instruments – Palladium is used in dental and surgical instruments

• Photography – Along with platinum, palladium salts can be used to create black and white prints



Ruthenium Another metal that is part of the Platinum group, is Ruthenium.

True or False? Jewellery can be made with ruthenium.

It is false! Jewellery is not manufactured in pure ruthenium, however, ruthenium is a very effective alloy.

Properties of ruthenium


• Atomic symbol: Ru




• Hardness: 6.5

My ring does not have ruthenium. Ru sure?

Uses of ruthenium

Let us look at the uses of ruthenium:

• Platinum and palladium can be hardened with ruthenium

• It is also used to plate other metals (adding a metal coating)

• By adding 0,1% of ruthenium to titanium, it improves its corrosion resistance by a hundred times over

• Ruthenium oxides are versatile catalysts

Did you know?

Are any of you currently making notes with a Parker pen?

I hope you are not currently chewing on your pen right now… Did you know that ruthenium is used in some Parker pens

like the parker 51 – it consists of 96,2% ruthenium and 3,8% iridium. Just so you also know, Ruthenium is highly toxic and

should never be ingested.

Gold and silver Next, we will look at our last 2 metals from the precious metals that we use in jewellery.

Gold

With its beautiful, rich colour, Gold has been used for centuries by people to decorate themselves.

But first, how old is gold? Almost as gold as the hills!

Can you believe that it dates to 3100 B.C? In the code of Menes, the founder of the first Egyptian dynasty, we have evidence

of a gold/silver ratio. In this code, it is stated that ‘one part of gold is equal to two and one-half parts of silver in value.’ This

is our earliest of a valued relationship between gold and silver.

Properties of gold


• Atomic symbol: Au


• Melting temperature: 1337.58°C


• Hardness: 2.5



I dropped a bar of gold on my foot… Au!

Characteristics of gold

• Resilience: against corrosion and will not tarnish

• Durable: due to its density of 19.3g per cm³

• Malleability: highly versatile as gold is extremely soft and ductile

• Purity: gold is only 99,95% pure as it consists of other small traces of silver, copper, mercury, and palladium

• Colour: these “impure” elements give gold its distinctive colour

Let’s KARATe

So, what is a karat? Karat is the amount of pure gold in an alloy. Karat signifies proportion and carat signifies weight (so do

not get those 2 terms mixed).

Pure gold:

• Is only 99.95% pure gold (24k)

• Too soft for most uses

• Alloyed with other metals to achieve desired hardness

• Silver and copper are the most common alloys used for gold

Uses of gold

• Electronic industry: due to its resistance to corrosion and easy processing, gold is used in electrical appliances

• Food: in the form of gold foil as a food colourant for example confectionery coatings and is considered non-toxic

• Dentistry: gold is used for fillings or dentures due to its resistance to corrosion

• Medical: gold salts are used to treat rheumatism therapy

• Investment: gold is an international currency in the form of bars and coins

Silver Our last precious metal is silver and dates to 3000 BC.

Pure silver is too soft to manufacture jewellery. Sterling silver is most used in jewellery and is 92,5% pure silver with 7,5%

copper.

Not everyone can afford platinum and gold; so, the silver lining… Silver is also a Precious metal!

Properties of silver


• Atomic symbol: Ag


• Melting temperature: 961.78°C


• Hardness: 2.5

Joke time again! What do you call dragon with no silver? A dron!! (no ag)

Characteristics of silver

• Silver is soft, ductile, and malleable

• It has a lustrous, bright metallic colour

• It also has the highest thermal conductivity of all metals

• Silver tarnishes when exposed to sulfur compounds present in water and air

• And is a non-toxic metal



Mirror mirror!

Silver makes the best mirrors:

• In the visible spectrum of metals used in mirrors, silver has the best surface reflectivity

• German chemist, Justus von Liebig, invented the process “silvering”

• A thin layer of silver is deposited onto a glass surface with a chemical reduction of silver nitrate. The glass protects

the silver from oxidation, corrosion, and oxidation. And thanks to the silver, we get a flawless reflection

• Since aluminium does not require protection of the glass, Aluminum is also known for “silvering” for precision-

mirrors

Uses of silver

• Higher quality silver is used for jewellery and silverware

• In batteries: silver is used as silver cadmium, electrical contacts, silver-zinc, and solder

• The photography industry uses about 30% of silver produced and is mostly used silver nitrate (halide salts)

• Colour images as well as black and white images have used silver from the early beginnings of photography

• Silver is also used in the electrical industry: computer keyboards use electrical contacts and silver circuits are

made with silver paint and because of silver’s properties, it is ideal to be used as catalyst in oxidation reactions

• Lastly, silver is also known to be used in dentistry for fillings

Did you know that silver has antibacterial properties?

Silver can be used as a food additive and colouring. And it used to be used during long journeys to prevent milk from

spoiling

Types of silver

Fine:

• Which is 999 pure silver

• With small amounts of lead, copper, iron, and other metals

Sterling:

• Which is 925 pure silver

• And the copper forms the other 75 (Copper s added to silver since pure silver is too soft for most uses; giving it a

higher hardness and better working qualities.)

• Coins in Britain before 1920 was made from 925 parts silver and 75 parts copper. This is where the name “sterling”

derived from

Britannia:

• 983 pure silver

• The rest: usually copper

• Used in holloware

• Too soft for jewellery

Coin silver:

• 900 pure silver

• Was the standard alloy for silver coinage in the USA

• Now it is occasionally used in jewellery

Continental European:

• 830 pure silver

• Accepted by many European countries for jewellery, holloware and flatware

• With the correct type of solder and preparations, this type of silver can be soldered without difficulties



Work in metal Now that we have explored precious metals and their capabilities, we will have a look at the basic techniques of working in

metal. This will just be an introduction but join me for Module 2 where we will dive deep into these manufacturing terms. I

do hope you will be joining me!

Basic skills

We will start with the basics skills we use on the bench. It is very important to have a comprehensive foundation on these

manufacture terms. Sometimes I need to remind myself that I cannot go for 0 to 100 in 60 seconds. So never skip the

basics as you could miss vital steps in the manufacturing and design process.

We will start with the very first skills you learn on the bench. These fundamental skills work together, and you must master

them all. One cannot be done without the other.

Piercing

Piercing is the art of sawing within a piece and creating negative spaces.

Drilling

Drilling is the art of creating openings for decorative designs, for riveting and to insert a saw blade through sheet metal. We

mostly use the standard twist drill bits.

Sawing

At the bench, the jeweller’s saw is one the most frequently used tool. Sawing is essential for creating the desired outline of

a piece, to create intricate patterns, to resize a ring or to create jump-links. It is vital to master accurate sawing to optimise

your metal usage and minimise metal loss.

Filling

Filing is an essential skill to learn on the bench and the sooner you learn to control your hand movements for filing, the

better! Files are very important for shaping, smoothing metal and finishing pieces. Incorrect filing techniques waste time

and metal.

Forge and form

Thanks to the malleability of precious metals, we can forge and form metal into desired shapes with a variety of

techniques.

Basic techniques for forming and forming metals include:

Hammering

In a jewellery factory, a goldsmith has about an average of 8 different types of used… speaking of a goldsmith, the ‘smith’

is derived from the verb ‘to smite’ meaning to hit! Quite fitting don’ you think?

Doming

Doming is a basic technique to create convex or concave jewellery pieces

Bending

Bending is an essential technique in jewellery creation. Bending requires pliers, forging hammers, anvils, mandrels and of

course, your metal MUST be annealed.



Chasing & repoussé

The art of creating intaglio effects by creating relief and embossed effects with the use of a pitch bowl, chasing tools and

hammers.

Decorating surfaces

Decorative surface techniques include:

Engraving

The art of carving in metal

Metal inlay

The process of inserting/fusing of one metal into another metal of a contrasting colour (also known as Zogan)

Etching

The chemical process of creating decorative designs, texture, or patterns on metal surfaces

Roll printing

The process of creating a ‘sandwich’ of precious metal sheet and a brass plate, and then inserting textures/patterned

material in between. This sandwich is then put through a rolling mill, leaving behind the pattern on the precious metal

sheet.

Mokumé

The process of layering 2 or more colour metal alloys together. This fusion creates a woodgrain effect.

Granulation

An ancient technique of covering a metal surface with tiny shapes (usually round metal beads)

Niello

An alloy of sulfur, copper, silver, and lead. The result is black metal.



References • Bellevue Rare Coins. 2020. TOP TEN FACTS EVERYONE NEEDS TO KNOW ABOUT

PALLADIUM. [online] Available at: https://www.bellevuerarecoins.com/top-ten-facts-

everyone-needs-to-know-about-palladium/

• Contributor, S., 2020. Facts About Silver. [online] livescience.com. Available at:

https://www.livescience.com/37040-silver.html

• Design, C., 2020. 75 Silver Facts: How Many Do You Know? | Claddagh Design. [online]

Claddaghdesign.com. Available at: https://www.claddaghdesign.com/from-the-

workshop/75-silver-facts/

• Ganoksin. 2020. Manufacturing Jewelry In Platinum Some Basic Facts - Ganoksin.

[online] Available at: https://www.ganoksin.com/article/manufacturing-jewelry-

platinum/

• Ganoksin. 2020. The Concept Of Preciousness - Ganoksin Jewelry Making Community.

[online] Available at: https://www.ganoksin.com/article/concept-of-preciousness/

• Lazy Penguins. 2020. Top 10 Most Expensive Alcohol In The World. [online] Available

at: https://lazypenguins.com/top-10-most-expensive-alcohol-in-the-world/

• Lenntech.com. 2020. Palladium (Pd) - Chemical Properties, Health And Environmental

Effects. [online] Available at: https://www.lenntech.com/periodic/elements/pd.html

• Lenntech.com. 2020. Ruthenium (Ru) - Chemical Properties, Health And

Environmental Effects. [online] Available at:

https://www.lenntech.com/periodic/elements/ru.htm#:~:text=All%20ruthenium%2

0compounds%20should%20be,volatile%2C%20and%20to%20be%20avoided.

• Lenntech.com. 2020. Silver - Ag - Chemical Properties, Health And Environmental

Effects. [online] Available at: https://www.lenntech.com/periodic/elements/ag.html

• Manhattan Gold & Silver. 2020. Fun Facts About Palladium - Manhattan Gold & Silver.

[online] Available at: https://www.mgsrefining.com/blog/2018/01/30/fun-facts-

about-palladium/

• Manhattan Gold & Silver. 2020. Silver And Mirror Making - Manhattan Gold & Silver.

[online] Available at: https://www.mgsrefining.com/blog/2013/07/03/silver-and-

mirror-

making/#:~:text=Of%20all%20the%20metals%20used,makes%20the%20very%20b

est%20mirrors.&text=The%20layer%20of%20silver%20produces,corrosion%2C%20

oxidation%2C%20and%20scratches.

• McCreight, T., n.d. Complete Metalsmith.

• Pappas, S., 2020. Facts About Palladium. [online] livescience.com. Available at:

https://www.livescience.com/36991-palladium.html

https://www.bellevuerarecoins.com/top-ten-facts-everyone-needs-to-know-about-palladium/

https://www.bellevuerarecoins.com/top-ten-facts-everyone-needs-to-know-about-palladium/

https://www.livescience.com/37040-silver.html

https://www.claddaghdesign.com/from-the-workshop/75-silver-facts/

https://www.claddaghdesign.com/from-the-workshop/75-silver-facts/

https://www.ganoksin.com/article/manufacturing-jewelry-platinum/

https://www.ganoksin.com/article/manufacturing-jewelry-platinum/

https://www.ganoksin.com/article/concept-of-preciousness/

https://lazypenguins.com/top-10-most-expensive-alcohol-in-the-world/

https://www.lenntech.com/periodic/elements/pd.html

https://www.lenntech.com/periodic/elements/ru.htm#:~:text=All%20ruthenium%20compounds%20should%20be,volatile%2C%20and%20to%20be%20avoided

https://www.lenntech.com/periodic/elements/ru.htm#:~:text=All%20ruthenium%20compounds%20should%20be,volatile%2C%20and%20to%20be%20avoided

https://www.lenntech.com/periodic/elements/ag.html

https://www.mgsrefining.com/blog/2018/01/30/fun-facts-about-palladium/

https://www.mgsrefining.com/blog/2018/01/30/fun-facts-about-palladium/

https://www.mgsrefining.com/blog/2013/07/03/silver-and-mirror-making/#:~:text=Of%20all%20the%20metals%20used,makes%20the%20very%20best%20mirrors.&text=The%20layer%20of%20silver%20produces,corrosion%2C%20oxidation%2C%20and%20scratches





https://www.livescience.com/36991-palladium.html



References

• Provident Metals. 2020. 70 Gold And Silver Quotes Every Precious Metals Investor

Should Know. [online] Available at: https://www.providentmetals.com/knowledge-

center/precious-metals-resources/gold-silver-quotes.html

• Provident Metals. 2020. History And Uses Of Palladium In Human Culture. [online]

Available at: https://www.providentmetals.com/knowledge-center/collectible-

coins/palladium-history.html

• Physical Gold. 2020. 15 Famous Quotes About Gold | Physical Gold. [online] Available

at: https://www.physicalgold.com/insights/15-famous-quotes-about-gold/

• Physical Gold. 2020. 8 Amazing Physical Properties Of Gold | Physical Gold Ltd.

[online] Available at: https://www.physicalgold.com/insights/physical-properties-

of-gold/

• Quora.com. 2020. What Is The Most Malleable Metal? - Quora. [online] Available at:

https://www.quora.com/What-is-the-most-malleable-metal

• Rsc.org. 2020. Gold - Element Information, Properties And Uses | Periodic Table.

[online] Available at: https://www.rsc.org/periodic-table/element/79/gold

• Ross, R., 2020. Facts About Platinum. [online] livescience.com. Available at:

https://www.livescience.com/39144-platinum.html

• Staff, L., 2020. Facts About Ruthenium. [online] livescience.com. Available at:

https://www.livescience.com/34836-ruthenium.html

• Sweatt, L., 2020. 19 Quotes About Facing Your Fears | SUCCESS. [online] SUCCESS.

Available at: https://www.success.com/19-quotes-about-facing-your-fears/

• TDN Creations. 2020. Characteristics And Uses Of Silver. [online] Available at:

https://www.tdncreations.com/blog/jewelry-education/characteristics-and-uses-

of-silver

• ThoughtCo. 2020. Get Facts About The Element Ruthenium. [online] Available at:

https://www.thoughtco.com/ruthenium-facts-ru-element-606589

• ThoughtCo. 2020. Know Your Elements: Gold Facts. [online] Available at:

https://www.thoughtco.com/gold-facts-606539

• Untracht, O., 2011. Jewelry. London: Robert Hale.

https://www.providentmetals.com/knowledge-center/precious-metals-resources/gold-silver-quotes.html

https://www.providentmetals.com/knowledge-center/precious-metals-resources/gold-silver-quotes.html

https://www.providentmetals.com/knowledge-center/collectible-coins/palladium-history.html

https://www.providentmetals.com/knowledge-center/collectible-coins/palladium-history.html

https://www.physicalgold.com/insights/15-famous-quotes-about-gold/

https://www.physicalgold.com/insights/physical-properties-of-gold/

https://www.physicalgold.com/insights/physical-properties-of-gold/

https://www.quora.com/What-is-the-most-malleable-metal

https://www.rsc.org/periodic-table/element/79/gold

https://www.livescience.com/39144-platinum.html

https://www.livescience.com/34836-ruthenium.html

https://www.success.com/19-quotes-about-facing-your-fears/

https://www.tdncreations.com/blog/jewelry-education/characteristics-and-uses-of-silver

https://www.tdncreations.com/blog/jewelry-education/characteristics-and-uses-of-silver

https://www.thoughtco.com/ruthenium-facts-ru-element-606589

https://www.thoughtco.com/gold-facts-606539

Professional Diploma in Jewellery Design Magics of Metallurgy

Documents

Transcript of Professional Diploma in Jewellery Design Magics of Metallurgy