Ornamental tortoise shell is obtained from the carapace or shield of the hawksbill turtle found in the Malay Archipelago, West Indies and Brazil. The colour is mottled and mainly a translucent yellow with brown mottling.

Generally thicker shells are used to make jewellery which is brown in color with white spots.

Chemical Composition: 

Complex Protein (keratin)

Classification / Type: 

Obtained from the carapace of a sea turtle.

Colors / Varieties: 

Mottled yellow and brown.

Transparency: 

Translucent to Opaque.

Crystal System / Forms: 

None. Amorphous.

Hardness: 

2.5

Specific Gravity: 

1.29

Cleavage / Fracture: 

None / Uneven.

Optic Character: 

A.G.G.

Lustre: 

Oily to waxy.

Refractive Index / Birefringence: 

1.55 / Nil.

Pleochroism: 

None.

Dispersion: 

None.

Magnification: 

Mottled sections show spherical spots of color. Larger numbers of dots give rise to deeper shades of color.

U.V. Fluorescence: 

Yellow portions give blue white fluorescence.

Spectrum: 

None.

Treatment (Enhancement): 

Colored impregnation (dyeing)

Specific Tests: 

• Sectile and brittle.
• Thermoplastic nature which softens in boiling water; used to produce large sheets.
• Excessive heat darkens the color.
• Burnt hair odor.

Synthesis: 

None.

Simulants (with separation tests): 

• Most commonly plastic (bakelite).
• Dust and scrapings of tortoise shell are softened and moulded, also dyed to produce darker colors.
• Doublet - tortoise shell on a plastic base.

Sources: 

Shell of turtles which are found at Indonesia, Indian Ocean, Malay Archipelago, Brazil and West Indies.

Cuts & Uses: 

Cabochons, used for inlay work, carvings, decorative combs and other items.