On this page
UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Trade name: colour / appearance variety · Natural identity; treatment status unknown
Carnelian
Also known asCornelian
Orange-red Chalcedony; heating to alter colour is common and can deepen the red tone, so natural colour should be confirmed by a certificate. 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.
Questions people ask about Carnelian
Every sentence below is followed by the registered fact it rests on; answers add no new facts and promise no outcome.
Q1Is carnelian usually dyed or heated?
Red and brown chalcedony is commonly dyed or heat-treated in the trade to enhance its colour, so natural colour has to be told apart from treated colour.G&G Summer 2020 · G&G Spring 2020AGTA marks carnelian heated for colour as needing only normal care.AGTA Gemstone Information Manual, 17th ed.Carnelian dyed for colour is marked as needing special care.AGTA Gemstone Information Manual, 17th ed.
Q2How can you tell if carnelian is real or natural in colour?
Colour and banding alone do not show whether the hue is natural or produced by dyeing or heating, so appearance cannot settle it; that takes instrumental examination.G&G Summer 2014 · CIBJO Gemstone Book 2022As a chalcedony, carnelian has a refractive index of about 1.53–1.54 and a specific gravity of about 2.48–2.65.G&G Summer 2020Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.What this page can answer
Q3What gives carnelian its orange-red colour?
Carnelian is the orange-red to brownish-red variety of chalcedony, and its red is associated with iron compounds such as hematite and goethite.G&G Fall 2013The tone varies with the iron content and with any treatment.G&G Fall 2013 · G&G Summer 2020 +1
Q4Can carnelian fade in the sun?
For dyed carnelian, CIBJO notes that strong light may fade it or return it to its original colour, so it should not be worn or left in strong light for long periods.CIBJO Gemstone Book 2022
Q5How does carnelian form?
Like other chalcedony, it forms as silica-rich fluids fill cavities or cracks in rock, layer by layer from the rim toward the centre.G&G Fall 2013 · G&G Spring 1982Its settings include voids and gas cavities in volcanic rock.G&G Fall 2013 · G&G Spring 1982
Q6What does carnelian symbolize, and does it have healing powers?
There is no scientific evidence that carnelian has healing powers: the UK advertising regulators ASA and CAP state that they have not seen evidence that crystal therapy can treat medical conditions.ASA/CAP guidance (UK)Its recorded cultural role is as a birthstone: the U.K. National Association of Jewellers lists it as an alternative for July.Cultural records
Sources cited in these answers ASA/CAP guidance (UK)
What this page can answer
This page covers
- How Carnelian 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 CarnelianIdentification points from the research literature; how far lab testing can go
- Treatments and enhancements of CarnelianThe enhancements and treatments the GB/T and JJA/AGL tables list
- Caring for and wearing CarnelianCleaning, heat, chemicals and light, as the cited sources give them
- Hardness, density and refractive index of CarnelianEach value with its source and check date
- Carnelian 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?
- Listing and disclosing CarnelianThe listing name to use; what must be disclosed before sale
- Standard clauses that define CarnelianWhich 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
Carnelian is the orange-red to brownish-red variety of chalcedony (microcrystalline quartz), and its genesis follows the chalcedony parent material: silica-rich fluids fill voids or fissures in the host rock cyclically from the rim toward the centre, precipitating layer by layer. Its red colour is associated with iron compounds — in banded chalcedony, red or brown-red zones are coloured by Fe compounds such as hematite and goethite. Besides natural colouration, red/brown chalcedony is commonly dyed or heat-treated in the trade to enhance colour, so natural and treated colour must be distinguished during identification. For the Fe-rich red chalcedonic agate of Sidi Rahal, crystallization was induced by Fe3+-rich fluids and lasted millions of years in stages.
Scope: Used to explain how the orange-red chalcedony variety carnelian inherits the cavity-filling origin of chalcedony, the iron source of its red colour, and the need to distinguish natural from dyed/heated material.
Sources G&G Fall 2013 · G&G Spring 1982 · G&G Summer 2020 +1
- Agates from Morocco: Gemological Characteristics and Proposed Origin (Gems & Gemology, Fall 2013, Vol. 49, No. 3)
- The Natural Formation and Occurrence of Green Quartz (Gems & Gemology, Spring 1982, Vol. 18, No. 1)
- Quench-Crackled Dyed Blue Chalcedony Resembling Larimar (Gems & Gemology, Summer 2020, Vol. 56, No. 2, Lab Notes)
- Dyed Chalcedony Imitation of Chrysocolla-in-Chalcedony (Gems & Gemology, Spring 2020, Vol. 56, No. 1)
Where it forms
Voids and vesicles in volcanic rock (geodes, vugs), filled cyclically by silica-rich fluids to form chalcedony.
Sources G&G Fall 2013 · G&G Spring 1982
Fe-rich fluid settings: Fe compounds (hematite, goethite) colour the red/brown-red zones, and Fe3+-rich fluids are thought to have induced crystallization.
Sources G&G Fall 2013 · G&G Summer 2020 · G&G Spring 2020
- Agates from Morocco: Gemological Characteristics and Proposed Origin (Gems & Gemology, Fall 2013, Vol. 49, No. 3)
- Quench-Crackled Dyed Blue Chalcedony Resembling Larimar (Gems & Gemology, Summer 2020, Vol. 56, No. 2, Lab Notes)
- Dyed Chalcedony Imitation of Chrysocolla-in-Chalcedony (Gems & Gemology, Spring 2020, Vol. 56, No. 1)
How it forms, step by step
Silica-rich fluids enter voids or fissures in the host rock.
Fluids circulate from the rim toward the centre, precipitating silica layer by layer as fibrous microcrystalline quartz (chalcedony).
Fe compounds (hematite, goethite) are distributed through the matrix, colouring parts of it red to brown-red.
Sources G&G Fall 2013 · G&G Summer 2020 · G&G Spring 2020
- Agates from Morocco: Gemological Characteristics and Proposed Origin (Gems & Gemology, Fall 2013, Vol. 49, No. 3)
- Quench-Crackled Dyed Blue Chalcedony Resembling Larimar (Gems & Gemology, Summer 2020, Vol. 56, No. 2, Lab Notes)
- Dyed Chalcedony Imitation of Chrysocolla-in-Chalcedony (Gems & Gemology, Spring 2020, Vol. 56, No. 1)
Later (and commercially) red/brown chalcedony may be dyed or heat-treated to enhance colour, requiring separate identification.
Sources G&G Summer 2020 · G&G Spring 2020 · G&G Fall 2013
- Quench-Crackled Dyed Blue Chalcedony Resembling Larimar (Gems & Gemology, Summer 2020, Vol. 56, No. 2, Lab Notes)
- Dyed Chalcedony Imitation of Chrysocolla-in-Chalcedony (Gems & Gemology, Spring 2020, Vol. 56, No. 1)
- Agates from Morocco: Gemological Characteristics and Proposed Origin (Gems & Gemology, Fall 2013, Vol. 49, No. 3)
Link to appearance
Translucent chalcedony from orange-red to brownish-red, its colour coming from the distribution of Fe compounds, with tone varying with iron content and any treatment.
Sources G&G Fall 2013 · G&G Summer 2020 · G&G Spring 2020
- Agates from Morocco: Gemological Characteristics and Proposed Origin (Gems & Gemology, Fall 2013, Vol. 49, No. 3)
- Quench-Crackled Dyed Blue Chalcedony Resembling Larimar (Gems & Gemology, Summer 2020, Vol. 56, No. 2, Lab Notes)
- Dyed Chalcedony Imitation of Chrysocolla-in-Chalcedony (Gems & Gemology, Spring 2020, Vol. 56, No. 1)
Timescale
Sidi Rahal agate (chalcedonic) crystallization lasted millions of years and proceeded in stages; the moganite-to-low-quartz transformation generally occurs over tens of millions of years and can serve as a relative age indicator.
Sources G&G Fall 2013 · G&G Spring 1982 · G&G Summer 2020
- Agates from Morocco: Gemological Characteristics and Proposed Origin (Gems & Gemology, Fall 2013, Vol. 49, No. 3)
- The Natural Formation and Occurrence of Green Quartz (Gems & Gemology, Spring 1982, Vol. 18, No. 1)
- Quench-Crackled Dyed Blue Chalcedony Resembling Larimar (Gems & Gemology, Summer 2020, Vol. 56, No. 2, Lab Notes)
Related base materials
- Chalcedony: colour variety | Carnelian is the orange-red/reddish-brown variety of chalcedony
- Agate: Commonly occurs as the red variety of banded chalcedony (agate)
Supporting findings
Carnelian inherits the chalcedony parent-material genesis, forming as silica-rich fluids fill voids or fissures cyclically from the rim toward the centre.
Evidence grade AScope: Describes the filling model; not a location-by-location account of carnelian.
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Asia
- Gujarat, IndiaOnly the title and bibliographic record were retrievable
Sources Antiquity (Insoll & Bhan, 2001)
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 how far testing can go on this page, the origin determination guide and the overview of recorded localities.
Causes of colour and optical effects
Carnelian is the orange-red to brownish-red variety of chalcedony; its red colour is associated with Fe compounds such as hematite and goethite.
Evidence grade AScope: The iron colour-cause is drawn from studies of Fe-rich zones in banded chalcedony, not specifically the carnelian trade name.
How it is identified
For carnelian, colour and banding by themselves do not reveal whether the hue is natural or produced by dyeing or heating, so visual appearance cannot settle naturalness or treatment; a trustworthy identification and any treatment ruling call for instrumental examination at a qualified gem laboratory, and this entry is no basis for self-testing.
Evidence grade AScope: Appearance cannot replace identification; naturalness, dyeing or heat treatment must be determined at a qualified gem laboratory, and this entry is not a self-testing basis.
Sources G&G Summer 2014 · CIBJO Gemstone Book 2022
Other research findings
Red/brown chalcedony is commonly dyed or heat-treated in the trade to enhance colour, and identification must distinguish natural from treated colour.
Evidence grade BScope: The cited sources document that chalcedony can be coloured with many dyes but the examples are blue; red dyeing/heating is not directly documented there.
As a chalcedony, carnelian has a refractive index of about 1.53–1.54 and specific gravity of about 2.48–2.65.
Evidence grade AScope: Laboratory ranges for chalcedony; individual specimens may differ slightly.
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The authoritative sources do not specifically discuss carnelian; its colour and treatment information is extrapolated from banded-chalcedony and blue-chalcedony dyeing studies.
- The boundary between carnelian and red agate, and whether regional carnelian is heat-treated, are not defined in the cited sources.
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
- Carnelian
GB/T 16552—2017 5.1.1 c) · CIBJO Gemmological Laboratories Book 2024 §7.2.1.41 “Carnelian (Cornelian)”
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Heated / Heat-treated, Filled / Fracture-filled (via parent material), Dyed
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
Carnelian is Orange-red chalcedony; use "Carnelian" for listings, and disclose any known treatments.
What this means for you
Before buying, check the recommended listing name "Carnelian" and any disclosed treatments on this page, and ask the seller for a grading report if in doubt.
Known uncertainty
- Last reviewed
- 2026-09-01
Care and wear
Normal care for every gemstone (CIBJO Gemstone Book §6.1), in brief:
- Handle it gently.
- Store pieces apart when not worn, so they cannot scratch each other.
- Clean with warm soapy water and a soft brush.
- Use ultrasonic cleaners only with caution.
The §6.1 wording and the full list of §6.2 special-care letters cited on this page are on the general gem care page.
Care
Carnelian — care (light): may fade or revert to its original colour in strong light; do not wear or leave it in strong light for extended periods.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code f
- Treatment state
- treated
- Only after these treatments
- dyeing
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Cornelian, p.71; §6.2 f (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Carnelian — care (special care): heated for colour: normal care.
AGTA Gemstone Information Manual, 17th ed.
- Treatment state
- treated
- Only after these treatments
- heating
Source & check 2026-09-26
- Source
- AGTA Gemstone Information Manual, 17th edition (August 2026) (AGTA): p.VIII, Gemstone Information Chart, Chalcedony Carnelian H, CARE REQUIRED / SPECIAL ADVICE (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Carnelian — care (special care): dyed for colour: special care (SC).
AGTA Gemstone Information Manual, 17th ed.
- Treatment state
- treated
- Only after these treatments
- dyeing
Source & check 2026-09-26
- Source
- AGTA Gemstone Information Manual, 17th edition (August 2026) (AGTA): p.VIII, Gemstone Information Chart, Chalcedony Carnelian D, CARE REQUIRED / SPECIAL ADVICE (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.
Common care questions and matching entries
Care of Carnelian depends on the treatment state. TreatedFor treated stones, specifically dyed ones, the CIBJO Gemstone Book (2022) states that they may fade or revert to their original colour in strong light, so do not wear or leave them in strong light for long periods, and the AGTA Gemstone Information Manual, 17th edition, states that colour produced by dyeing needs special care. For treated stones, specifically heated ones, the AGTA Gemstone Information Manual, 17th edition, states that colour produced by heating needs only normal care.
This table scrolls sideways on narrow screens.
| Question | Matching entries |
|---|---|
| Light and display | may fade or revert to its original colour in strong light; do not wear or leave it in strong light for extended periods |
Care entries by treatment state
The same entries grouped by the treatment state each applies to; each links to its full wording and source. Letters are CIBJO special-care codes, explained on the gemstone care page.
treated (Only after these treatments: dyeing)
- may fade or revert to its original colour in strong light; do not wear or leave it in strong light for extended periods §6.2 f
- dyed for colour: special care (SC)
treated (Only after these treatments: heating)
Treatments and identification leads
One row per treatment, with three standards side by side: how often it occurs and how stable it is (CIBJO), its category in GB/T 16552—2017 Table B.1 (this site's paraphrase) and how the JJA/AGL 2025 table lists it. Each CIBJO value links to its entry under “Testing and market”, where the wording and source are given in full.
This table scrolls sideways on narrow screens.
| Treatment | Market frequency (CIBJO) | Stability (CIBJO) | GB/T 16552 category | JJA/AGL listing | Identification leads |
|---|---|---|---|---|---|
| Heating | — | — | Optimization | — | — |
| Filling | — | — | Graded — see §5.4.1, Table 1 | — | — |
| Dyeing | — | — | Optimization | — | — |
| heating / colouring | — | — | — | heating / colouring | — |
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16552—2017 Table B.1 (row for Chalcedony); JJA/AGL 2025
Whether a treatment has to show in the name differs between the two rule sets (this site’s paraphrase):
- GB/T 16552—2017: a method classed as treatment has to be stated in the name itself — the method put before the name, or added in brackets after it; a method classed as optimization does not need to appear in the name, though one marked “Optimization (annotation required)” still has to be noted in the quality documents. Source: §5.4.2.1 a), b); §5.4.2.2 a)
- CIBJO Gemstone Book 2022: no longer splits treatments into ones that need specific disclosure and ones that need only general disclosure: every treatment is to be disclosed, and the seller tells the buyer which treatment was used and what special care it calls for. Source: §4.2.5 Note 2, §4.2.5.1, pp.14–15
What this table covers
What this page can give
- Registered treatments, their stability and how often they occur (see the table above)
- Identification leads for each treatment, for use when sending a stone for testing
VerifyNames, standards, technical facts, clauses and sources
Names
Besides Carnelian, the name register records "Carnelian" and "Cornelian", for which no restriction on use as a name is recorded (CIBJO Gemmological Laboratories Book 2024 §7.2.1.41 “Carnelian (Cornelian)”; CIBJO Gemstone Book 2022 Annex 8 “Cornelian”; JJA/AGL Gemstone Nomenclature 2025 p.11).
Standard and listing namesThe national-standard name corresponding to Carnelian is chalcedony (GB/T 16552—2017 Table A.2, row Chalcedony (Agate/Jasper)); the name carnelian itself is not listed in the national standard, and the suggested listing name is Carnelian. Trade and mineralogical namesThe trade name/synonym is Carnelian, with the synonym Cornelian; the CIBJO Gemmological Laboratories Book 2024 records it as Carnelian (Cornelian), and Cornelian also appears in the name register of the JJA/AGL Gemstone Nomenclature 2025. The mineralogical name is orange-red chalcedony. Names in four languagesNames are given in four languages: Simplified Chinese, Traditional Chinese, English (Carnelian) and Japanese (a katakana transliteration and a kanji name). Institution usageOn authority wording, the FTC text on file has no wording for this name (checked), and GIA, CIBJO and Gem-A wording is unchecked; bodies without a recorded wording show the entry's own English name Carnelian, which does not represent the position of those bodies. Japanese namesJapan's GSJ formal name is not yet verified by this site; the entry's own Japanese name is the katakana and kanji pair.
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 (2) | ||||
| CarnelianEnglish | market name | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
| CornelianEnglish | synonym | matched automatically | no restriction recorded | CIBJO Gemmological Laboratories Book 2024 §7.2.1.41 “Carnelian (Cornelian)”; CIBJO Gemstone Book 2022 Annex 8 “Cornelian”; JJA/AGL Gemstone Nomenclature 2025 p.11 |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- カーネリアン／紅玉髄 (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)
- 玉髓 (GB/T 16552—2017 Table A.2, row “Chalcedony(Agate/Jasper)”)
- Mineralogical name
- Orange-red chalcedony
- Trade names and synonyms
- Cornelian (synonym)
Four-language names
- 简体中文
- 红玉髓
- 繁體中文
- 紅玉髓
- English
- Carnelian
- 日本語
- カーネリアン／紅玉髄
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Quartz and chalcedony materials
- Identity tier
- Trade name: colour / appearance variety
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
Treatments listed by standards
GB/T 16552-2017, Annex B, Table B.1
Under the “Chalcedony (Agate/Jasper)” row of Table B.1: Heating Optimization; Filling Graded — see §5.4.1, Table 1; Dyeing Optimization. The full row, with the effect column, is on the Chalcedony page.
What Table B.1 is, and how the “see 5.4.1” grades are defined: see the GB/T 16552: optimization vs treatment page.
JJA/AGL (Japan) table of principal gem names, 2025
This table scrolls sideways on narrow screens.
| Gem name | Species | Colour | Listed in the table | Notes |
|---|---|---|---|---|
| Cornelian | Quartz | red to reddish brown | the source lists no untreated tier; heating / colouring (Heated / Heat-treated, Dyed) |
JJA/AGL definitions and nomenclature (2025 revision), table of principal gem names, p.11
How to read the JJA/AGL table: see the Gem treatments page.
What it is and how it's identified
The material facts for Carnelian are registered from the cited clause for "chalcedony (including agate and jasper, the whole class)", not measured on Carnelian alone. For the chalcedony class: structure cryptocrystalline aggregate, compact and massive, and may also form spherulitic, radiating or microfibrous aggregates; Mohs hardness 5–7; cleavage none; density 2.5–2.77 g/cm³; optical character anisotropic aggregate; refractive index 1.535–1.539, where the site note explains that the cited clause has finer sub-ranges and the overall value is used; birefringence not measurable on an aggregate; for untreated Carnelian, pleochroism is not measurable on an aggregate, per the chalcedony class; both iridescence and the cat's-eye effect can occur, per the chalcedony class; for untreated Carnelian, lustre is vitreous to greasy, per the chalcedony class. Chemical composition, luminescence, UV-visible spectrum, infrared spectrum and magnification are whole-class features registered for chalcedony (including agate and jasper, the whole class); see the material facts on the Chalcedony entry.
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 chalcedony, including agate and jasper (the whole class), so they are not repeated on the Carnelian page; see the material facts on the Chalcedony entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Carnelian (how to read class-level values).
Structure
Carnelian — structure (overall): a cryptocrystalline aggregate, dense and massive in habit; it may also form spherulitic, radial or finely fibrous aggregates.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Carnelian — Mohs hardness: 5–7
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
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Carnelian — cleavage: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Carnelian — density: 2.5–2.77 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Carnelian — optic character: anisotropic aggregate
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Carnelian — refractive index: 1.535–1.539
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
- General note
- the clause has finer ranges
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Carnelian — birefringence: not measurable on an aggregate
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Carnelian — pleochroism: not measurable on an aggregate
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Carnelian — optical effect (iridescence): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Carnelian — optical effect (chatoyancy): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
- CIBJO definitions
- chatoyancy
Quality factors
Carnelian — quality factor (lustre): vitreous to greasy
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (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): 1.537 / 2.63; Closest values: 1Amethyst 1.548 / 2.67, 2Charoite 1.554 / 2.66, 3Changhua Stone 1.56 / 2.6, 4Shoushan Stone 1.56 / 2.7, 5Balin Stone 1.56 / 2.55
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
The CIBJO laboratory protocol covers Carnelian under “Chalcedony” (§6.1.16): see identification on the Chalcedony entry; the required tests are listed on the CIBJO laboratory protocol table for Chalcedony.
How far testing can go
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Clause-level definitions
Carnelian is defined directly in CIBJO Gemmological Laboratories Book 2024, with the term registered as Carnelian (Cornelian). The clause gives the mineral species as quartz and the mineral/gem variety as Carnelian (cornelian), with the CIBJO wording quoted in full under Clause-level definitions on this page. The cross-check shows it is defined directly by CIBJO, and no identically named English entry was found in this edition of the GB/T annex.
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| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Carnelian (Cornelian) | 7.2.1.41 | Brownish orange or brownish red, yellow-orange to orangish red, translucent chalcedony | Defined directly by CIBJO; no identically named English entry was found in this edition of the GB/T annex. |
Evidence and sources
Authority basis and clause sources
Sources
Further reading
Recorded cultural contexts
The U.K. National Association of Jewellers chart lists Carnelian as an alternative for July. This records trade-association convention only; it does not establish material identity, natural origin, treatment, provenance, or effect.
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| Publisher or holder | Region | From / period | Source and locator |
|---|---|---|---|
| National Association of Jewellers | United Kingdom | — | National Association of Jewellers, “Zodiac Birthstones Jewellery: Star Signs, Gemstones and Their Meaning” (web page, consulted 2026-08-22) Zodiac birthstone chart, July row: Carnelian (Alternative) |
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 Quartz on this site: 74 entries listed by this site's parent-entry links; synthetic, treated and similar entries carry their recorded state after the name; this page (Carnelian) is marked.
- Quartz
Sub-entries (57)
- Agate
Sub-entries (1)
- Amethyst
- Ametrine
- Aventurine Quartz
- Aventurine Quartz / Green Aventurine
- Banded Agate
- Black Agate
- Bloodstone / Heliotrope
- Blue Lace Agate
- Carnelian
- Chalcedony
Sub-entries (2)
- Chrysoprase
- Citrine
- Clear Quartz / Rock Crystal
- Coated Quartz
- Colourless to White Quartz (brand name: Azeztulite)
- Crazy Lace Agate
- Dendritic Agate
- Dyed Agate (Treated: dyed)
- Elestial Quartz / Skeletal Quartz
- Eye Agate
- Flower Agate / Cherry Blossom Agate
- Green Quartz
- High-clarity quartz with golden needle-like inclusions
- Included Quartz
- Jasper
Sub-entries (1)
- Madeira Citrine
- Malachite Agate
- Morion / very dark Smoky Quartz
- Moss Agate
- Moss Chalcedony
- Multi-inclusion Quartz
- Onyx (banded chalcedony)
- Phantom Quartz
- Prase
- Prasiolite / Green Quartz
- Quartz Cat’s-eye
- Quartz claimed to be from the Himalayas
- Quartz Crystal
- Quartz with dark needle-like inclusions
- Quartz with fine fibrous inclusions
- Quartz with flower-like inclusions
- Quartz with golden needle-like inclusions
- Quartz with green needle-like inclusions
- Quartzite Jade
- Quartzose Jade
- Red Agate
- Rock Crystal
- Rose Quartz
- Rutilated Quartz
- Sard
- Sardonyx
- Silicified Asbestos
Sub-entries (2)
- Hawk’s Eye
- Tiger’s Eye
Sub-entries (1)
- Smoky Quartz
- Smoky Quartz (brown variety)
- Strawberry Quartz
- Yellow-green Quartz
- Agate
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| Page | Content | Status |
|---|---|---|
| Browsing family | Quartz and chalcedony materials | Live |
| Treatments recorded for this material | Heated / Heat-treated, Filled / Fracture-filled (via parent material), Dyed | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Carnelian 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.