On this page
UnderstandWhat it is, what people ask, how far this page goes
Natural organic and biogenic materials · Organic or biogenic material · Natural identity; treatment status unknown
Turtle Shell
Also known asTortoise shell
Horny shell material from turtles, listed as “turtle shell” in Table A.3 of GB/T Annex A; the entire sea turtle family is in CITES Appendix I. This page compares how the major standards and institutions name it, what must be disclosed when selling it, whether it can be worn every day, how it is treated and identified, and which source each conclusion comes from.
Price, rarity and origin are outside the scope of this wiki.
What this page can answer
This page covers
- How Turtle Shell forms and what gives its colourFormation setting, process and timescale, each finding graded and sourced
- How to identify Turtle ShellIdentification points from the research literature; how far lab testing can go
- Caring for and wearing Turtle ShellCleaning, heat, chemicals and light, as the cited sources give them
- Hardness, density and refractive index of Turtle ShellEach value with its source and check date
- Turtle Shell in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name; and: Has any of GIA, FTC, CIBJO or Gem-A put a name for it on record here?
- Name origin and history of Turtle ShellHow people have used it, with museum objects
- Listing and disclosing Turtle ShellThe listing name to use; what must be disclosed before sale
- Standard clauses that define Turtle ShellWhich clause defines it, each cross-checked
What we cannot conclude
- Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.
- Geographic origin, unless an origin report accompanies the item.
- Price, rarity or investment value: this wiki covers naming and disclosure only.
Material research: formation, causes and history
What authoritative sources say about how this material forms, what causes its colour and optical effects, where its name comes from and how people have used it. Each statement carries an evidence grade and its sources; it describes the material in general, not any specific piece.
How it forms
Turtle shell, known in Chinese as gui jia, is the keratinous shell substance of turtles and tortoises; being animal-derived, it is organic, or biogenic, material rather than a mineral species. Taking marine turtles as the example: the shell is built of scutes, in which β-keratin protein predominates, with mineral constituents — calcium phosphate and calcium sulfate — dispersed through it. NOTE: for material derived from a species, the species has to be established first. What tradition calls tortoiseshell comes chiefly from marine turtles, above all the Hawksbill Turtle (Eretmochelys imbricata), whose scutes supply it; because marine turtles sit in CITES Appendix I (Eretmochelys imbricata is currently listed in CITES Appendix I), trade in their products is forbidden, and the legality of any source turns on the species and on permits. During processing the scutes are boiled, the mineral content is driven off, and a flexible β-keratin component remains, ready to be shaped.
Scope: Applies to an overview of the identity and composition of "turtle shell" as a keratinous shell material of turtles (taking the β-keratin and mineral components of sea turtle scutes as an example), and gives the species-first CITES compliance boundary; makes no determination on the species or compliance of specific samples.
Sources Journal article (tortoiseshell ATR-IR) · CITES Checklist
Where it forms
Biogenic: formed by growth of the turtle's scutes (keratinous), not a geological setting.
Sources Journal article (tortoiseshell ATR-IR) · CITES Checklist
How it forms, step by step
The turtle grows scutes (shell plates) on its body surface.
Sources Journal article (tortoiseshell ATR-IR)
β-keratin predominates in the scutes; calcium phosphate and calcium sulfate form the mineral component scattered through them.
Sources Journal article (tortoiseshell ATR-IR)
The species must first be identified to establish the CITES/compliance status.
Sources Journal article (tortoiseshell ATR-IR)
(Processing) boiling the scutes drives off their mineral content, and the flexible β-keratin that remains is then shaped.
Sources Journal article (tortoiseshell ATR-IR)
Link to appearance
Marine turtle scutes are β-keratin material and may show brown to amber appearance; NOTE: appearance alone cannot distinguish marine turtle, horn and imitation materials, which requires testing (e.g. infrared spectroscopy and DNA).
Sources Journal article (tortoiseshell ATR-IR) · CITES Checklist
Timescale
The sources give no absolute timescale for the material's formation (it is a product of animal growth).
Sources Journal article (tortoiseshell ATR-IR) · CITES Checklist
Human use and museum objects
The collection evidence shows objects explicitly recorded as turtle-shell material dating mainly to the 17th-20th centuries: a 17th-century Japanese inrō on a tortoiseshell body (Met 91.1.2153a–c) and late 19th-early 20th-century Pacific ornaments (Met 1979.206.1473, 1999.47.62, 1978.412.739). Ceramics or photographs named "tortoiseshell" are excluded. Marine turtles are CITES Appendix I; this record serves historical identification only and concerns no modern trade.
Evidence grade AScope: Applies to objects explicitly recorded as turtle shell / tortoiseshell; cultural attribution follows museum records and is not extended by inference.
Sources The Met 1979.206.1473 · The Met 1999.47.62 · The Met 1978.412.739 +3
- The Metropolitan Museum of Art — Kapkap (pendant or head ornament) (1979.206.1473)
- The Metropolitan Museum of Art — Dala (Pendant or Head Ornament) (1999.47.62)
- The Metropolitan Museum of Art — Pendant or Head Ornament (Kapkap) (1978.412.739)
- The Metropolitan Museum of Art — Tortoiseshell and Basketry Inrō (91.1.2153a–c)
- The Metropolitan Museum of Art — Stick of tortoiseshell (C.I.X.50.1.3)
- The Metropolitan Museum of Art — Locket and Chain (2000.559a, b)
Objects explicitly recorded as turtle-shell material (turtle shell / tortoiseshell) in these collections are mostly modern. From the Pacific come ornaments of turtle shell with Tridacna shell: a kapkap from New Ireland (Met 1979.206.1473, late 19th-early 20th century, recorded material includes turtle shell), a dala from the Solomon Islands (1999.47.62) and a kapkap from the Admiralty Islands (1978.412.739). From Japan there is a 17th-century inrō built on tortoiseshell under a lacquered rattan "net" (acc. 91.1.2153a–c) and a stick of tortoiseshell of 1700-1950 (acc. C.I.X.50.1.3). A European example is a tortoiseshell locket and chain of about 1870 (acc. 2000.559a, b). Note that many objects whose titles contain "tortoiseshell" are in fact ceramics named for a "tortoiseshell" glaze or pattern (e.g. Jizhou ware teabowls) or a photograph, and not turtle-shell material; these are excluded here. Turtle shell is a species-derived material whose species must first be identified; marine turtles are listed in CITES Appendix I (the hawksbill, Eretmochelys imbricata, being Appendix I) and trade in their products is prohibited — this record serves historical object identification only and concerns no modern trade.
Sources The Met 1979.206.1473 · The Met 1999.47.62 · The Met 1978.412.739 +3
- The Metropolitan Museum of Art — Kapkap (pendant or head ornament) (1979.206.1473)
- The Metropolitan Museum of Art — Dala (Pendant or Head Ornament) (1999.47.62)
- The Metropolitan Museum of Art — Pendant or Head Ornament (Kapkap) (1978.412.739)
- The Metropolitan Museum of Art — Tortoiseshell and Basketry Inrō (91.1.2153a–c)
- The Metropolitan Museum of Art — Stick of tortoiseshell (C.I.X.50.1.3)
- The Metropolitan Museum of Art — Locket and Chain (2000.559a, b)
Scope: A museum object evidences only the existence and date of that artefact itself; it does not establish widespread ancient use of the material, nor does it attest the origin, naturalness, or treatment of any modern specimen. Marine turtles are CITES Appendix I; the collection objects are historical holdings that concern no modern trade. Cultural attribution follows museum records and is not extended by inference.
Objects cited
- The Met 1979.206.1473Tridacna shell, turtle shell, fiber
- The Met 1999.47.62Tridacna shell, turtle shell, fiber, glass bead
- The Met 1978.412.739Tridacna shell, turtle shell, fiber, glass bead
- The Met 91.1.2153a–cInrō: single case; tortoiseshell under rattan “net” covered with lacquer (urushi); ojime: flower petals, brushwood; patinated copper with mixed-metal inlays; netsuke: turtle; carved wood
- The Met C.I.X.50.1.3Tortoiseshell
- The Met 2000.559a, bTortoiseshell
How it is identified
Tortoiseshell-type material resembles imitations and other keratinous substances in appearance, so sight cannot reliably separate them. Identification is done in a laboratory by instrumentally testing structure and composition; for doubtful or unresolved samples, trade guidance calls for prudent disclosure, and the conclusion should come from an accredited body.
Evidence grade AScope: Tortoiseshell-type identification requires professional laboratory testing, with prudent disclosure for doubtful samples.
Sources CIBJO Gemstone Book 2022
Other research findings
Using marine turtles as the example: their shell consists of scutes. β-keratin protein accounts for most of each scute, and dispersed inside it are mineral constituents — calcium phosphate and calcium sulfate.
Evidence grade AScope: Describes marine turtle scute composition; not all turtle shells.
Sources Journal article (tortoiseshell ATR-IR)
"Turtle shell" is the keratinous shell material of turtles/tortoises; for a species-derived material the species must first be identified.
Evidence grade BScope: Defines the material source and species-first principle; not a specific species.
Sources Journal article (tortoiseshell ATR-IR)
Marine turtles are listed in CITES Appendix I; the Hawksbill Turtle (Eretmochelys imbricata) is currently listed in Appendix I, and trade in their products is banned.
Evidence grade AScope: The species-first compliance boundary; the appendix level differs by species and must be verified per species.
(Processing) boiling the scutes drives off their mineral content, and the flexible β-keratin that remains is then shaped.
Evidence grade AScope: Describes the processing of scutes; a traditional practice, not all products.
Sources Journal article (tortoiseshell ATR-IR)
The turtle shell traditionally worked as tortoiseshell comes from the shell plates of marine turtles, predominantly the hawksbill. The CITES Appendices list the whole sea-turtle family (Cheloniidae spp.) in Appendix I.
Evidence grade AScope: Covers shell from sea turtles (Cheloniidae) only; the status of shell from other turtle families depends on their own listings. It does not cover national law or permits for any particular item.
Sources CITES Appendices (2026) · Journal article (tortoiseshell ATR-IR)
Under the CITES Convention, trade in specimens of Appendix I species is subject to particularly strict regulation and is to be authorised only in exceptional circumstances; among the conditions for an import permit, the importing State's Management Authority must be satisfied that the specimen is not to be used for primarily commercial purposes.
Evidence grade AScope: Summarises the Convention text only. CITES governs international trade; each Party may adopt stricter domestic measures, and exemptions such as those in Article VII are not covered here. Not legal advice for any particular item.
Sources CITES Convention text
A CITES listing covers more than the live animal: when a species is in Appendix I, the whole animal, live or dead, and all its parts and derivatives fall under the same Appendix, which is how worked turtle shell comes within the listing. In the Convention, 'trade' means export, re-export, import and introduction from the sea.
Evidence grade AScope: Summarises the Convention text only. CITES governs international trade; each Party may adopt stricter domestic measures, and exemptions such as those in Article VII are not covered here. Not legal advice for any particular item.
Sources CITES Appendices (2026) · CITES Convention text
The CITES Appendices valid from 5 March 2026 list the whole sea-turtle family (Cheloniidae spp.) in Appendix I; the hawksbill turtle is covered by this family listing rather than by an entry under its own name. A listing covers the whole animal, live or dead, and its parts and derivatives fall in the same Appendix.
Evidence grade AScope: States only what is printed in the CITES Appendices valid from 5 March 2026 and their interpretation notes; shell from other turtle families depends on their own listings, and national law, exemptions and permits are not covered. Not legal advice.
Sources CITES Appendices (2026)
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- "Turtle shell" is an animal-derived (turtle) material that the sources consulted do not define in a single mineralogical way; the species must be identified before anything is said about the material.
- The cited peer-reviewed source uses marine turtles (predominantly the Hawksbill Turtle, Eretmochelys imbricata) as the example; no dedicated sources for other turtles/tortoises have been found.
- CITES appendix level differs by species (here Eretmochelys imbricata is I); no sources for other turtles have been found.
- The relation between "turtle shell" (generic turtle shell) and "tortoiseshell" (specifically marine turtle scute material) must be stated cautiously; this record asserts no equivalence.
Methodology
- Origin determination and its limits
- Quality grading and value factors
- How gemmology became a technical discipline
Evidence grades
- A
- Standards bodies, government geological surveys, peer-reviewed research and museum records
- B
- Institutional educational material
- C
- Specialist databases or cautious readings
A statement is never graded above its strongest source.
This section is LumaLark's own factual restatement of public authoritative sources, credited item by item; it contains no verbatim excerpts, images or third-party logos.
DecideListing name, disclosure, care and treatments
- Suggested listing name
- Turtle shell (only where lawful and the species documentation is complete)
GB/T 16552—2017 Table A.3 “Tortoise Shell”, 5.2.1 a) · CIBJO Gemmological Laboratories Book 2024 §7.2.2.11
Construction or treatment status
Natural identity; treatment status unknown
Related:Disclosure and cautions
This page cannot answer
Natural? · Origin · Price
A lab report settles these; this wiki covers naming and disclosure.
Related:What this page can answer
Answer at a glance
"Turtle Shell" is a market name rather than a mineral species name; before using it, verify: Laboratory identification required before the name is used.
Evidence
- GB/T · Table A.3, row 龟甲 (Turtle Shell)
What this means for you
Before buying, check the recommended listing name "Turtle shell (only where lawful and the species documentation is complete)" and any disclosed treatments on this page, and ask the seller for a grading report if in doubt.
Known uncertainty
- This entry's exact material identity is not fully settled.
- See “Disclosure and cautions” above
- Last reviewed
- 2026-09-01
Trade-name ruling
- Laboratory identification required before the name is used.
- Suggested listing name
- Turtle shell (only where lawful and the species documentation is complete)
Care and wear
Care
Turtle Shell — care (cleaning): GIA names tortoise shell among the materials that must not go into an ultrasonic cleaner.
GIA 4Cs blog (2015)
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- GIA 4Cs blog, “Gems and Ultrasonic Cleaners” (2015-04-10): Section: main text (locator checked 2026-10-06)
- Fact checked on
- 2026-10-06
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Common care questions and matching entries
Each question links to the matching entries on this page; whether they answer it fully, go by the entry wording.
This table scrolls sideways on narrow screens.
| Question | Matching entries |
|---|---|
| Can it go in an ultrasonic or steam cleaner? | GIA names tortoise shell among the materials that must not go into an ultrasonic cleaner |
VerifyNames, standards, technical facts, clauses and sources
Names
Besides Turtle Shell, the name register records "Tortoise shell", for which no restriction on use as a name is recorded (GB/T 16552—2017 Table A.3 “Tortoise Shell”; CIBJO Gemmological Laboratories Book 2024 §7.2.2.11; CITES Appendices 2026 CHELONIIDAE).
Standard and listing namesThe Chinese formal name for Turtle Shell comes from GB/T 16552—2017 Table A.3; the suggested listing name is Turtle Shell (only where legal and species documentation is complete). Trade and mineralogical namesThe trade name and synonym is written Tortoise shell; the formal English name GB/T 16552 Table A.3 gives for it is Tortoise shell, and the tortoise shell in the CIBJO Gemmological Laboratories Book 2024 refers to marine turtles; the mineralogical name can be paraphrased as horny shell material from turtle or tortoise species. Names in four languagesThe four-language names cover Simplified Chinese, Traditional Chinese, English (Turtle Shell) and Japanese; the GSJ (Japan) wording for the entry's own Japanese name is not yet verified by this site. Institution usageOn authority wording, the name on record in the CIBJO Gemmological Laboratories Book 2024 is Tortoise shell; the FTC and CIBJO texts have no wording for Turtle Shell (checked), and GIA and Gem-A are unchecked. Bodies without a record show the entry's own English name, which does not represent their position.
Name register
Every name recorded for this entry, with how it is classified, whether it may be matched to this entry automatically, whether it may be used as a product name, and the clause it rests on.
This table scrolls sideways on narrow screens.
| Name | Type | Matching | Use as a name | Basis |
|---|---|---|---|---|
| no restriction recorded (1) | ||||
| Tortoise shellEnglish | synonym | matched automatically | no restriction recorded | GB/T 16552—2017 Table A.3 “Tortoise Shell”; CIBJO Gemmological Laboratories Book 2024 §7.2.2.11; CITES Appendices 2026 CHELONIIDAE; Note: Related high-risk name “Coral, giant clam shell”. |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- 鼈甲／べっこう (not yet checked for this body — the entry's own Japanese name is shown)
- Chinese formal name
- 龟甲 (GB/T 16552—2017 Table A.3)
- Mineralogical name
- Keratinous shell material from turtle/tortoise species
- Trade names and synonyms
- Tortoise shell (synonym)
Four-language names
- 简体中文
- 龟甲
- 繁體中文
- 龜甲
- English
- Turtle Shell
- 日本語
- 鼈甲／べっこう
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural organic and biogenic materials
- Browsing family
- Other animal-derived materials
- Identity tier
- Organic or biogenic material
- Mineral chemical class
- Not applicable
- Construction or treatment status
- Natural identity; treatment status unknown
What it is and how it's identified
The material facts for Turtle Shell are: composed of protein and other organic matter, with the main elements C, H, O and N; amorphous. Mohs hardness 2–3, cleavage none; density 1.26–1.35 g/cm³, from the clause value 1.29 with tolerance +0.06/−0.03, from which the limits are derived. Optic character isotropic, birefringence none; refractive index 1.54–1.55 is the reading commonly obtained by the spot method, a typical value rather than an absolute limit. When untreated, pleochroism is none; fluorescence is bluish white in some colourless and yellow parts; magnification shows a mottled structure made up of spherical particles; lustre is dull, greasy to waxy; for stability, nitric acid dissolves Turtle Shell, it does not react with hydrochloric acid, it melts when touched with a hot needle, giving off a smell like burnt hair, and it softens in boiling water. In the infrared spectrum, vibrations of functional groups in protein and other organic matter produce characteristic bands in the mid-infrared region.
Registered material facts
Each row carries its own source and check date and can be cited on its own; “—” means the cited source gives no value, not “none”.
Definition
Turtle Shell — composition (chemistry): protein and other organic matter, built mainly of C, H, O and N.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Structure
Turtle Shell — structure (overall): amorphous (not crystalline)
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Durability
Turtle Shell — Mohs hardness: 2–3
GB/T 16553—2017
Reference points on this site: Talc 1–3, Fluorite 4, Apatite 5–5.5, Orthoclase 6–6.5, Topaz 8, Diamond 10 (Source: GB/T 16553—2017); Gypsum 1.5–2, Calcite 3, Quartz 7 (Source: Handbook of Mineralogy); Corundum 9 (Source: GIA Gem Encyclopedia (care guide))
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Turtle Shell — cleavage: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Turtle Shell — stability: dissolves in nitric acid and does not react with hydrochloric acid; melts when touched with a hot needle and smells like burning hair; softens in boiling water.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Physical properties
Turtle Shell — density: 1.26–1.35 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 1.29, with a stated tolerance of +0.06 / -0.03. The range shown here is worked out from that.
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Optical
Turtle Shell — optic character: isotropic material
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Turtle Shell — refractive index: 1.54–1.55
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives this as a value commonly read by the spot (distant-vision) method. It is a common value, not an absolute limit.
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Turtle Shell — birefringence: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Turtle Shell — transparency: translucent.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Turtle Shell — pleochroism: none
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Turtle Shell — fluorescence (overall): colourless, yellow: in part blue-white.
GB/T 16553—2017
UV fluorescencein part: blue-whitecolourless, yellowDots are illustrative colours built from the colour names, not measured values
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Turtle Shell — spectrum (UV-visible): non-characteristic
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Turtle Shell — spectrum (infrared): Vibrating functional groups (radicals) in protein and other organic matter produce the diagnostic mid-IR bands.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-22
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-22)
- Fact checked on
- 2026-09-22
Turtle Shell — magnification: mottled structure made up of spherical grains
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
body colour2 sources compared
Turtle Shell — body colour: yellow and brown mottling, sometimes black or white. The shell of the hawksbill turtle is commonly called hawksbill shell.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- Qualification
In chapter 5 of GB/T 16553—2017, the colour entries of Serpentine, Shoushan Stone, Turquoise and other variety clauses also name yellow or a yellowish colour.
- General note
- colour alone is not identity
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Turtle Shell — body colour: mottled, yellowish or reddish and brown.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Bytownite, Fire Opal, Hessonite and other entries also name yellow or a yellowish colour.
- General note
- colour alone is not identity
Source & check 2026-09-26
- Source
- Fact checked on
- 2026-09-26
How the sources relate
- GB/T 16553—2017 and CIBJO Gemmological Laboratories Book 2024
Both describe yellow and brown mottling. GB/T 16553—2017 adds that black or white sometimes occurs; the CIBJO Gemmological Laboratories Book adds a reddish tone.
Quality factors
Turtle Shell — quality factor (lustre): dim, greasy to waxy
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.9 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
This material (RI / SG midpoints): 1.545 / 1.31; Closest values: 1Plastic 1.58 / 1.3, 2Amber 1.54 / 1.03, 3Black Coral 1.565 / 1.71, 4Mammoth Ivory 1.53 / 1.75, 5Ivory 1.535 / 1.85
Show the full chart (330 registered materials)
Outside the full chart's range, drawn as triangles at the edge (RI / SG midpoints): Hematite 3.045/5.12, Synthetic Rutile 2.76/4.26, Rutile 2.753/4.23, Synthetic Moissanite 2.67/3.22
Testing and market
For identifying Turtle Shell, the CIBJO laboratory protocol requires checks focused on structure, protein smell (hot point) and plastic (common imitation). Structure is a check item listed in the protocol, the hot point test corresponds to protein smell, and plastic is the common imitation; the specific methods for each required test are in the protocol table on the laboratory testing page.
The tests the CIBJO laboratory protocol requires for this material, and what each method means, are in the protocol table on the laboratory testing page: §6.2.27.
How far testing can go
Turtle Shell — what the CIBJO laboratory protocol says to watch for: structure, protein smell (hot point), plastic (common imitation).
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- any treatment state
Source & check 2026-09-26
- Source
- Fact checked on
- 2026-09-26
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Clause-level definitions
Turtle Shell has a clause-level definition in the CIBJO Gemmological Laboratories Book 2024, registered under the entry name Tortoise shell; the CIBJO wording for Tortoise shell is quoted in full under Clause-level definitions on this page. Cross-check result: defined directly by CIBJO; also present in the GB/T annex.
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Tortoise shell | 7.2.2.11 | Tortoise shell is an organic, protein material (hard keratin), which forms the mottled, yellowish or reddish and brown, translucent plates (‘scutes’) covering the shells of certain species of marine turtle. The best known and the finest tortoise shell comes from the hawksbill sea turtle. Distinction criteria | Defined directly by CIBJO; also present in the GB/T annex. |
Evidence and sources
Authority basis and clause sources
Sources
- CIBJO – The World Jewellery Confederation. Gemmological Laboratories Book (Blue Book), Gemmological Commission 2024-1.
- CIBJO – The World Jewellery Confederation. The Gemstone Book (Blue Book), 2022.
- SAMR / SAC (China). GB/T 16552—2017 Gems — Nomenclature.
- CITES Secretariat. Appendices I, II and III, valid from 5 March 2026.
Further reading
Related entries and topic cluster
Parent entry and related pages on this site. Rows marked “Planned” are suggested new content and have no link yet.
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| Page | Content | Status |
|---|---|---|
| Browsing family | Other animal-derived materials | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Turtle Shell entry are maintained by the LumaLark wiki and matched one by one to the standard clauses or institutional sources they cite: every fact carries its source (with a clause or page locator) and a check date, so it can be traced back to the original; clause-level definitions also carry a cross-check result. The entry exists so that buyers and sellers can check naming, disclosure and material facts item by item.