Identification of tortoiseshell (marine turtle shell)

Developed by the CITES Secretariat

GreenCustoms Knowledge Series No. 10

2

Questions to answer

• What is tortoiseshell?

• What part of the marine turtle is used?

• What kinds of tortoiseshell are in trade?

• How to identify tortoiseshell?

• How to identify imitation tortoiseshell?

3

Introduction

• All marine turtles (family Cheloniidae) are included in Appendix I of CITES

• All parts and derivatives in international trade are subject to the strictest CITES controls

• The attractive natural material known as 'tortoiseshell' is not derived from tortoises, but from marine turtles

3

4

Marine turtle shell

• The shell is comprised of two general sections, the dorsal (top) carapace and the ventral plastron

• The carapace is comprised of bony plates that are generally covered with scutes that are part of the outer skin

• These scutes are prized for making small objects or as decoration, and may be referred to in trade as bekko or tortoiseshell

4

5

Marine turtle shell

• The scutes have a structural function, as they overlap the seams between the shell bones and add strength to the shell

• The scutes are made up of a fibrous protein called keratin that also makes up the scales of other reptiles

• Scutes from several species may be used, but the main demand is for Hawksbill turtle Eretmochelys imbricata

5

6

Marine turtle shell

• The 13 back scutes are used

• Although whole carapaces may be traded as stuffed specimens, for bekko trade the scutes will be separated

7

Marine turtle shell

• Only the transparent/translucent part of the shell scute is valued

8

Marine turtle shell

• Polished whole shells are commonly traded

• Finished items made from the translucent portion of the scutes are also traded

• Raw scutes may be traded

9

Marine turtle shell

• Tortoiseshell has been used for a very long time, so many antique pieces exist

– Mention of tortoiseshell is made in classical Greek literature

– The Egyptians used to trade tortoiseshell with the Romans

– Tortoiseshell has been used in the making of Japanese musical instruments since the 8th Century

– Tortoiseshell was very popular in household items and art in 18th and 19th Century Europe

– Tortoiseshell has been commonly used in 20th Century items, from eyeglass frames to combs to guitar picks

9

10

10

Marine turtle shell

• Processed tortoiseshell is “nature’s plastic”

11

11

Marine turtle shell

• Tortoiseshell can be seen on many antique items

12

12

Marine turtle shell

• Tortoiseshell used in making Japanese musical instruments

13

Marine turtle shell

• It is probably not possible to tell the difference between antique tortoiseshell items and new ones by looking at the shell alone

• Antique items may require a pre-Convention certificate, or may qualify for the exemption for personal and household effects

– See Resolution Conf. 13.6 Implementation of Article VII, paragraph 2, concerning 'pre-Convention’ specimens

– See Resolution Conf. 13.7 (Rev. CoP14) Control of trade in personal and household effects

14

Marine turtle shell imitation

• Tortoiseshell has always been valued due to its beauty and rarity, so it is not surprising that imitation (fake) tortoiseshell has been around since adequate substitutes were first developed

– The first of these was celluloid, considered the first 'thermoplastic', developed in 1856

– Celluloid is the name of a class of compounds created from nitrocellulose and camphor, plus dyes and other agents

15

Marine turtle shell imitation

• Celluloid is easily molded and shaped, and it was first widely used as an ivory replacement

– Celluloid is highly flammable and also easily decomposes, and is no longer widely used

– Its most common uses today are the table tennis ball and guitar picks (plectra)

16

Marine turtle shell imitation

• Early imitation tortoiseshell made from celluloid is difficult to tell from real shell

17

Marine turtle shell imitation

• Imitation tortoiseshell is commonly seen today, usually made from modern plastics

18

Marine turtle shell imitation

• One method still used for creating imitation tortoiseshell for the construction of eyeglass frames and combs is to use a cellulose acetate resin cast in a large block

– It is a slow curing resin by design, which allows colored pigment resin sticks to be floated on the surface and dissolved in the resin to create the beautiful swirled patterns, often with multiple layers

– The block is then sliced very thinly

19

Marine turtle shell imitation

• One test for distinguishing real shell from celluloid imitation tortoise shell is to rub the article on a piece of cloth until it becomes warm, or hold the piece under hot water for around 30 seconds

• If the warmth brings out an odour of camphor or vinegar, it is a celluloid imitation

• As celluloid can be flammable, do not use a hot flame or a hot pin in trying to tell shell from plastic

19

20

Summary

• Tortoiseshell is made from the shell scutes of marine turtles

• As all marine turtles are included in Appendix I of CITES, trade in tortoiseshell is strictly controlled

• Because of its beauty and the ability to be molded and to change shape under heat, tortoiseshell was used as modern plastics are used today - this means many old household and decorative items may contain tortoiseshell

21

Summary

• Tortoiseshell has been particularly valued for making parts of musical instruments, art objects and furniture inlay

• Imitation tortoiseshell has been produced since the 1850s

• Imitations made from celluloid can be easily identified, but resins and plastics may be difficult to differentiate from genuine tortoiseshell

22

CITES SecretariatGeneva

www.cites.org