Tortoise Shell
Tortoise shell is an organic jewelry material made from the carapace of the hawksbill sea turtle. The name "bekko" (tortoise shell) is said to have originated during the Genroku era, when it was used as a cover name to evade sumptuary laws that prohibited luxury goods (the term literally refers to the shell of a soft-shelled turtle). Depending on the color and pattern, there are several types, including "banko" (spotted shell) with yellow and black mottled patterns, "shiroko" (white shell) consisting only of yellow parts, and "kuroko" (black shell). The hawksbill turtle is a species of sea turtle that inhabits tropical waters.
An organic material characterized by its contrasting mottled pattern and warm luster.
Basic Information
| English Name | Tortoise Shell |
|---|---|
| Japanese Name | Bekko |
| Chemical Composition | Keratin (Composition ratio: C:O:N+S = 6:2:1.5:0.5) |
| Hardness | 2.5 |
| Specific Gravity | 1.25 |
| Classification | Organic Gemstone (Animal origin) |
Characteristics & Variations
- Material: Refers to the shell of the hawksbill turtle.
- Types: Depending on color and pattern, it includes banko (yellow and black mottled), shiroko (yellow only), and kuroko (black).
Variants
- Soshiroko (Pure White Shell): Extremely rare albino hawksbill turtles exist that consist entirely of white shell without any mottled patterns. They are valued as biological specimens or highly rare taxidermy (they are not used as jewelry materials).
Processing, Treatment, Imitations & Related Info
Processing & Treatment:
- The carapace of a hawksbill turtle consists of 13 plates, which are skillfully bonded together during the manufacturing process.
- Because the shell softens and becomes pliable when heated, the plates can be joined together without adhesives.
- Coloring Treatment: Some pieces are created by bonding together shells that have been dyed or colored with lacquer.
Similar Materials:
- Wako (Japanese Shell): The shells of green sea turtles or loggerhead sea turtles are referred to as "Wako" in contrast to true bekko. The patterns are not as distinct as those of the hawksbill, and they are considered difficult to process because they are thinner and harder.
Related Information:
- Shoko Pattern: Natural patterns formed on the side of the shell that was in contact with the turtle's flesh.
- Powder Processing: Shells are ground into powder and molded into plates.
- Ranko (Egg Shell): A bekko imitation made by drying egg whites.
- How to Identify: When viewed through a loupe with light shining through, genuine bekko shows a fine, granular structure within the mottled pattern.
Important Note (Legal Restrictions): Japan signed the Washington Convention in 1973, and the import of tortoise shell was completely banned in 1993. Please be sure to comply with local laws and regulations regarding its handling. Additionally, as items may be subject to coloring or bonding, it is safest to verify that the explanation of the material's origin is consistent with its processing.