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Natural organic and biogenic materials · Organic or biogenic material · Natural identity; treatment status unknown
Red Coral
Also known asMoro Coral · Oxblood Coral · Sardinian Coral · Sciacca Coral
The red variety of Precious Coral. The trade-name table in Annex C §7.7 of the CIBJO coral book assigns Aka, Moro and Oxblood to Japanese red coral (Corallium japonicum), and Mediterranean, Sardinian and Sciacca to Mediterranean red coral (Corallium rubrum).
Also known as Sciacca Coral. 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 Red Coral forms and what gives its colourFormation setting, process and timescale; where its colour and optical effects come from, each finding graded and sourced
- How to identify Red CoralIdentification points from the research literature
- Hardness, density and refractive index of Red CoralEach value with its source and check date
- Red Coral 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 Red CoralHow people have used it, with museum objects
- Listing and disclosing Red CoralThe listing name to use; what must be disclosed before sale
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
Red coral is the collective term for the red kinds of precious coral, spanning several species; the species must be identified before the material is discussed. It is an animal-derived (biogenic) material: coral polyps secrete a biomineralized calcium carbonate skeleton, which is the material used as a gem. The overall chemical composition of coral is mainly calcium carbonate (about 82–87%) with minor magnesium. The red colour comes from carotenoid pigments. Red corals grow in warm, clean waters on the rocky sea bottom in low-light conditions, typically at depths of about 10–300 m, as deep-water species. Trade legality depends on species and permits: per SPECIES+, Corallium japonicum and others are currently listed in CITES Appendix III (at China's request, effective 01/07/2008); Corallium rubrum is not listed in any CITES Appendix.
Scope: Applies to explaining the biogenic origin, composition, colouration and occurrence of red coral as a multi-species precious coral, and its species-dependent CITES listing; not applicable to determining the specific species, locality, treatment or value from the name, and it does not constitute purchasing / compliance advice.
Sources CIBJO Coral Blue Book 2024 · GIA Reading List: Mediterranean Coral · CITES Checklist
Where it forms
Warm, clean, rocky sea bottom in low-light, deep-water settings (about 10–300 m).
Sources CIBJO Coral Blue Book 2024 · GIA Reading List: Mediterranean Coral
Deep-water species, in ecosystems distinct from shallow-water reef corals.
Sources CIBJO Coral Blue Book 2024 · GIA Reading List: Mediterranean Coral
How it forms, step by step
Coral polyps (a colony) grow and secrete biomineralized calcium carbonate, forming a branched hard skeleton.
Sources CIBJO Coral Blue Book 2024 · GIA Reading List: Mediterranean Coral
The skeleton is made of intermeshed calcium carbonate spicules; the red colour comes from carotenoid pigments.
Sources CIBJO Coral Blue Book 2024 · GIA Reading List: Mediterranean Coral
After harvesting, the skeletal branches are cut and polished for use as gem material.
Sources CIBJO Coral Blue Book 2024 · GIA Reading List: Mediterranean Coral
Link to appearance
When polished it shows an intense red colour and porcelainous lustre; but colour and appearance cannot substitute for species identification, and treatments such as dyeing must be disclosed.
Sources CIBJO Coral Blue Book 2024 · GIA Reading List: Mediterranean Coral · CITES Checklist
Timescale
The cited sources give no absolute age for red coral; it grows slowly over decades, but no specific figure is provided.
Sources CIBJO Coral Blue Book 2024 · GIA Reading List: Mediterranean Coral · CITES Checklist
Related base materials
- Corallium japonicum: CITES III
- Corallium rubrum: One of the species referred to as red coral (not listed in the CITES Appendices)
Supporting findings
Red coral is an animal-derived (biogenic) material: coral polyps secrete a biomineralized calcium carbonate skeleton, which serves as the gem material.
Evidence grade AScope: A biogenic-process statement; the specific species requires separate identification.
Sources GIA Reading List: Mediterranean Coral · CIBJO Coral Blue Book 2024
Red corals grow in warm, clean, rocky sea-bottom environments with low light, typically at depths of about 10–300 m, as deep-water species.
Evidence grade AScope: An occurrence description; the specific origin (e.g. Mediterranean, Pacific) requires separate determination and is a matter of opinion.
Sources GIA Reading List: Mediterranean Coral
Recorded localities
This is an organic material; its localities are the harvest or culture areas (waters or species ranges) recorded by authoritative sources.
Europe
- Waters off Sciacca, Sicily, ItalyDead coral branches found in 1885; trade term Sciacca coral
Sources CIBJO Coral Information Sheet
Seas and coasts
- Mediterranean Sea (off North Africa and Europe)Corallium rubrum; known in the trade as Sardinian coral
Sources CIBJO Coral Information Sheet · CIBJO Coral Blue Book 2024
- Waters off Japan
Sources CIBJO Coral Information Sheet
- Waters off Taiwan, China
Sources CIBJO Coral Information Sheet
These are localities recorded by authoritative sources, not an origin finding for any individual piece. The CIBJO Gemstone Book (2022, §4.2.3) says a place of origin names where a gem was mined or harvested, is a matter of opinion, does not imply a level of quality, and that cutting, processing or exporting centres must not be used to imply origin. See the origin determination guide and the overview of recorded localities.
Causes of colour and optical effects
The red colour of red coral is due to carotenoid pigments.
Evidence grade AScope: Describes the natural red colour; it does not imply that dyeing is absent, and treatments must be disclosed.
Sources GIA Reading List: Mediterranean Coral
Human use and museum objects
Coral objects in museum holdings date after the 16th century and continue into the modern era, e.g. a Peruvian coral necklace before 1532 (Cleveland Museum of Art, 1940.499) and a Qing Mandarin necklace (Cleveland Museum of Art, 1952.472); species are not resolved, and the evidence belongs to the parent material behind red coral.
Evidence grade AScope: Evidence belongs to the parent material behind red coral; species are unresolved and no exclusive claim is made for the name.
Sources Cleveland Museum of Art 1940.499 · The Met 2009.300.2984a–c
Museum objects catalogued as coral cluster after the 16th century and extend into the modern era, e.g. a Peruvian coral necklace before 1532 (Cleveland Museum of Art, 1940.499), a 1704 chasuble with accessories (The Met, 2009.300.2984a–c), a statue robe of ca. 1690–1720 (The Met, 43.164) and a Qing Mandarin necklace (Cleveland Museum of Art, 1952.472). Records mostly say only 'coral', without resolving species and without consistently recording colour, so the evidence belongs to the parent material behind red coral and is not exclusive to the name 'red coral'.
Sources Cleveland Museum of Art 1940.499 · The Met 2009.300.2984a–c
Scope: Museum objects attest only to the existence and date of the individual documented pieces; they do not evidence widespread ancient use of the material, nor the origin, naturalness or treatment of any modern specimen.
Objects cited
- Cleveland Museum of Art 1940.499coral
- The Met 2009.300.2984a–cSilk, linen, coral, metal, jet
- The Met 43.164Metal thread, coral beads
- Cleveland Museum of Art 1952.472jade and coral beads, pendants mounted in gold and enamel
- The Met 55.111.56Silver, enamel, coral
- Cleveland Museum of Art 1916.290silver, gilded; turquoise, coral and red glass
How it is identified
The appearance of red-coral can be imitated, so appearance alone cannot confirm it. Imitation coral lacks the chemical composition, physical properties or structure of natural coral; identification requires laboratory methods — examining internal features such as the different polished lustre of filled fissures at 10× magnification, together with instrumental testing of chemistry and structure — while dyed, filled, impregnated and coated treatments must be detected and disclosed at sale. Limitations: some treatments and imitations are visible only under magnification or instrumentation, and the conclusion must be issued by an accredited gemological laboratory through testing rather than inferred from appearance.
Evidence grade AScope: Identification and separation points; testing must be performed by an accredited gemological laboratory, and no self-test thresholds are given.
Sources CIBJO Coral Blue Book 2024 · CIBJO Gemstone Book 2022
Other research findings
Coral is made up chiefly of calcium carbonate (about 82–87%) plus a little magnesium; traces of calcium sulphate, iron oxide and assorted phosphates can also be present.
Evidence grade AScope: Composition of precious coral as a broad class; the exact proportions of a given species/sample require testing.
Sources CIBJO Coral Blue Book 2024
Red coral spans several species (e.g. Corallium japonicum, Corallium rubrum) whose identity must be established before the material is discussed; per the CITES Checklist, Corallium japonicum is in CITES Appendix III (at China's request, effective 01/07/2008), whereas Corallium rubrum is not listed in any CITES Appendix.
Evidence grade AScope: Species and CITES-level statement; CITES levels are current status, updated at CoPs, and trade legality depends on species and permits, not a blanket ban.
Sources CITES Checklist · CIBJO Coral Blue Book 2024 · GIA Reading List: Mediterranean Coral
The cited sources do not identify red coral as an independent mineral species—it is a biogenic material, not a single mineral; precious corals are limited to the three groups Corallium, Pleurocorallium and Hemicorallium of the family Corallidae.
Evidence grade AScope: An identity-boundary statement; it does not deny that an individual sample may contain inorganic mineral phases.
Sources CIBJO Coral Blue Book 2024
The CITES Appendices valid from 5 March 2026 do not list the red and pink coral family (Coralliidae) as a whole: they name four of its species in Appendix III, each submitted by China — Corallium japonicum and three species of the genus Pleurocorallium (P. elatius, P. konojoi and P. secundum). Mediterranean red coral (Corallium rubrum) is not named anywhere in those Appendices.
Evidence grade AScope: States only what is printed in the CITES Appendices valid from 5 March 2026 (the Appendix III column of the Coralliidae entry; the absence of Corallium rubrum was checked by a full-text search of the same document). Which species a given piece of red coral comes from can only be settled by testing; national law and permits are not covered. Not legal advice.
Sources CITES Appendices (2026)
Under the CITES Convention, Appendix III holds species that a Party identifies as subject to regulation within its own jurisdiction and for which it needs other Parties' co-operation in controlling trade; Parties may not allow trade in specimens of species in Appendices I, II or III except in accordance with the Convention. A listing covers the whole animal, live or dead, and its parts and derivatives fall in the same Appendix.
Evidence grade AScope: Summarises the Convention text and the interpretation notes of the Appendices only. CITES governs international trade; each Party may adopt stricter domestic measures, and exemptions are not covered here. Not legal advice for any particular item.
Sources CITES Convention text · CITES Appendices (2026)
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- Red coral is a multi-species biogenic material; the species must be established first, and the name cannot replace species identification or compliance review.
- CITES: Corallium japonicum and others are Appendix III (China's request), while Corallium rubrum is not listed; 'protected' is not a blanket trade ban—legality depends on species and permits.
- Not a judgement of origin, treatment, grade or value; origin is a matter of opinion.
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
- Red Coral (state the genus, species and any treatments)
CIBJO Coral Blue Book 2024 §5.78, §5.74 “Oxblood coral”, Annex C §7.7 · GB/T 16552 revision draft for comment (2023, not in force) Table A.3
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
"Red Coral" is a market name rather than a mineral species name; before using it, verify: Laboratory identification required before the name is used.
Evidence
- CIBJO · 5.78
What this means for you
Before buying, check the recommended listing name "Red Coral (state the genus, species and any treatments)" 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
- 2026-09-26
Trade-name ruling
- Laboratory identification required before the name is used.
- Suggested listing name
- Red Coral (state the genus, species and any treatments)
Care and wear
No care facts are recorded for this entry itself. Its parent material has care records: see Coral.
VerifyNames, standards, technical facts, clauses and sources
Names
Besides Red Coral, the name register records "Moro Coral", "Oxblood Coral", "Sardinian Coral" and "Sciacca Coral", for which no restriction on use as a name is recorded.
Recommended listing nameThe suggested listing name for Red Coral is Red Coral (state genus/species and treatment); the corresponding name in GB/T 16552—2017 Table A.3 is coral, and the original GB/T 16552—2017 does not list Red Coral. Trade and mineralogical namesThe mineralogical name is red precious coral, covering Corallium japonicum and Corallium rubrum. Trade names/synonyms include Oxblood Coral, Moro Coral, Sardinian Coral and Sciacca Coral. Names in four languagesNames are given in Simplified Chinese, Traditional Chinese, English (Red Coral) and Japanese (to be checked). Institution usageOn authority wording, FTC has been checked and its text does not use the wording Red Coral; GIA, CIBJO and Gem-A have not yet been verified; bodies that do not list Red Coral show the entry's own English name, which cannot represent the position of the bodies concerned. Japanese namesOn the GSJ (Japan) formal name, the entry has its own Japanese name (to be checked), and the wording used by GSJ (Japan) for it is not yet verified by this site.
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 (4) | ||||
| Moro CoralEnglish | market name | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
| Oxblood CoralEnglish | market name | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
| Sardinian CoralEnglish | market name | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
| Sciacca CoralEnglish | market name | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- 赤珊瑚（待核） (not yet checked for this body — the entry's own Japanese name is shown)
- GB/T naming counterpart (this name is not in the standard)
- 珊瑚 (GB/T 16552—2017 Table A.3)
- Mineralogical name
- Red precious coral (Corallium japonicum, Corallium rubrum)
- Trade names and synonyms
- Oxblood Coral (market name) · Moro Coral (market name) · Sardinian Coral (market name) · Sciacca Coral (market name)
Four-language names
- 简体中文
- 红珊瑚
- 繁體中文
- 紅珊瑚
- English
- Red Coral
- 日本語
- 赤珊瑚（待核）
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural organic and biogenic materials
- Browsing family
- Coral 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
Among the registered material facts for Red Coral, features such as chemical composition, fluorescence, UV-visible spectrum, infrared spectrum and magnification are written in the cited clause for calcareous coral and are not listed again for Red Coral; see the material facts on the Coral entry. As the cited GB/T 16553—2017 clause writes it for calcareous coral, the Mohs hardness of Red Coral is 3–4.5. As the cited clause writes it for calcareous coral, the density of Red Coral is 2.6–2.7 g/cm³; the cited clause gives 2.65 with a tolerance of ±0.05, from which the limits are derived. As the cited clause writes it for calcareous coral, the refractive index of Red Coral is 1.48–1.66, which the cited clause gives as the reading commonly seen by the spot method, a typical value rather than an absolute limit. For Mohs hardness, density and refractive index alike, it is stated that the cited clause is written for calcareous coral and the values are not measurements of Red Coral alone.
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”.
Chemical composition, luminescence, UV-visible spectrum, infrared spectrum, magnification: these whole-class features are given in the cited clause for calcareous coral, so they are not repeated on the Red Coral page; see the material facts on the Coral entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Red Coral (how to read class-level values).
Durability
Red Coral — Mohs hardness: 3–4.5
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
- What this covers
- calcareous coral
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.4 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Red Coral — density: 2.6–2.7 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- calcareous coral
- Qualification
The clause we cite gives 2.65, with a stated tolerance of ±0.05. The range shown here is worked out from that.
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.4 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Red Coral — refractive index: 1.48–1.66
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- calcareous coral
- 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 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.4 (locator checked 2026-09-26)
- 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.
This material (RI / SG midpoints): 1.57 / 2.65; Closest values: 1Scapolite 1.558 / 2.67, 2Changhua Stone 1.56 / 2.6, 3Amethyst 1.548 / 2.67, 4Balin Stone 1.56 / 2.55, 5Qingtian Stone 1.565 / 2.77
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
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.
- CIBJO – The World Jewellery Confederation. The Coral Book (Blue Book), 2024.
- SAMR / SAC (China). GB/T 16552—2017 Gems — Nomenclature.
- CITES Secretariat. Appendices I, II and III, valid from 5 March 2026.
- eCFR (United States). 16 CFR Part 23 — Guides for the Jewelry, Precious Metals, and Pewter Industries.
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.
Related-entry tree for Coral on this site: 12 entries listed by this site's parent-entry links; synthetic, treated and similar entries carry their recorded state after the name; this page (Red Coral) is marked.
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Coral materials | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Red Coral 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. The entry exists so that buyers and sellers can check naming, disclosure and material facts item by item.