On this page
UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Rock / mineral aggregate · Natural identity; treatment status unknown
Ammolite
Also known asAmmonite (conditional name) · Ammonite Shell (conditional name)
An organic gem material made from iridescent fossilized ammonite shell; only material from specific ammonite fossil layers may be called Ammolite. 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 Ammolite 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 AmmoliteHow far lab testing can go
- Treatments and enhancements of Ammolite1 registered treatments: status, stability, how common they are and identification leads
- Caring for and wearing AmmoliteCleaning, heat, chemicals and light, as the cited sources give them
- Ammolite in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name; and: Which of GIA, FTC, CIBJO and Gem-A have a name for it on record, and do those agree?
- Listing and disclosing AmmoliteThe listing name to use; what must be disclosed before sale
- Standard clauses that define AmmoliteWhich 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
Ammolite is a gem material of aragonite, recovered from the intensely iridescent fossil shells of ammonites and worked solely in Alberta, Canada. It comes from two extinct species, Placenticeras meeki and P. intercalare, which are restricted to particular beds of the Bearpaw Formation (Late Cretaceous, roughly 70–75 million years ago). Burial left the shell's original aragonite layer intact, and the iridescence it shows arises through interference of light. This layer is usually thin and easily damaged, so the great majority of ammolite is assembled into stones rather than used whole.
Scope: Applies to an overview of the fossil source, age, composition and colour origin of ammolite from the Bearpaw Formation of Alberta, Canada.
Sources G&G Spring 2001
Where it forms
Certain horizons of the Late Cretaceous Bearpaw Formation in Alberta, Canada — the only known source.
Sources G&G Spring 2001
After the ammonite died the shell was buried in marine sediment, and the aragonite shell layer was preserved during diagenesis.
Sources G&G Spring 2001
How it forms, step by step
Ammonites (Placenticeras meeki / P. intercalare) lived in Late Cretaceous seas about 70-75 million years ago and built aragonitic shells.
Sources G&G Spring 2001
The shells were buried in Bearpaw Formation marine sediment, and the aragonite layer was preserved as a fossil.
Sources G&G Spring 2001
The preserved aragonite layer produces iridescence through an interference phenomenon.
Sources G&G Spring 2001
Because the iridescent layer is thin and fragile, mined material is mostly fashioned into assembled stones for use as a gem.
Sources G&G Spring 2001
Link to appearance
Ammolite's rainbow colours (spectral hues from red to blue that change with angle) arise from interference in the aragonite shell layer, not from pigments.
Sources G&G Spring 2001
Timescale
The host ammonite shells are from the Late Cretaceous Bearpaw Formation, about 70-75 million years old.
Sources G&G Spring 2001
Related base materials
- Aragonite: Principal inorganic phase (a calcium carbonate polymorph)
Supporting findings
Ammolite is an aragonitic material won from the brightly iridescent fossil shells of ammonites of the extinct species Placenticeras meeki and P. intercalare; working has so far been confined to the Canadian province of Alberta.
Evidence grade AScope: States the locality and source species; not processing or grading.
Sources G&G Spring 2001
The gem material occurs solely within specific layers of the Bearpaw Formation, which is of Late Cretaceous age—roughly 70 to 75 million years old.
Evidence grade AScope: Limited to its stratigraphic occurrence; not analogous material elsewhere.
Sources G&G Spring 2001
Recorded localities
Authoritative sources name a single or principal locality.
North America
- Southern Alberta, CanadaAs of 2001; only from certain horizons of the Bearpaw Formation and only from Placenticeras meeki and P. intercalare
Sources Gems & Gemology Spring 2001
- St. Mary River valley, near Lethbridge, Alberta, CanadaDescribed as the source of most commercial Ammolite (2001)
Sources Gems & Gemology Spring 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
The iridescence of ammolite is caused by an interference phenomenon rather than by pigments.
Evidence grade AScope: Applies to its colour (optical) mechanism; not colour grading.
Sources G&G Spring 2001
Other research findings
Ammolite is a form of aragonite, a calcium carbonate polymorph, as a fossil material.
Evidence grade AScope: States the inorganic phase is aragonite; organic/trace constituents aside.
Sources G&G Spring 2001
Most ammolite is made into assembled stones, since the layer that produces the iridescence tends to be thin and easily broken.
Evidence grade AScope: Explains that the common assembled-stone form follows from the material's nature; not a value judgement.
Sources G&G Spring 2001
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- This record relies mainly on a single GIA monograph abstract; mining, grading and assembled-stone details are not covered.
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
- Ammolite
CIBJO Gemmological Laboratories Book 2024 §7.2.1.12 “Ammolite”
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Impregnated
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
Ammolite is often subjected to impregnation. Under GB/T 16552-2017, impregnation is graded by the material used, and must be stated in the name wherever it counts as a treatment (§5.4.1, Table 1). Do not assume it is unenhanced.
Evidence
- CIBJO · 7.2.1.12
What this means for you
Before buying, check the recommended listing name "Ammolite" and any disclosed treatments on this page, and ask the seller for a grading report if in doubt.
Known uncertainty
- See “Disclosure and cautions” above
- Disclosure rules for the treatments above can change as authorities update their standards; re-check before relying on this page.
- 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
Ammolite — care (cleaning): Some stones are susceptible to damage from ultrasonic cleaning. Do not expose them to ultrasonic cleaning.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code j
- Treatment state
- any treatment state
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Ammolite, p.33; §6.2 j (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Ammolite — care (chemicals): Some stones are particularly susceptible to attack by acids. Keep them away from acids.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code h
- Treatment state
- any treatment state
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Ammolite, p.33; §6.2 h (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Ammolite — care (chemicals): Treatments with dye, oil, resin, wax or plastic are not permanent; keep it away from all solvents (including dish-washing liquids), chemicals and heat.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code k
- Treatment state
- treated
- Only after these treatments
- impregnation
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Ammolite, p.33; §6.2 k (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Ammolite — care (wear): low hardness, so it scratches easily; wear with care; cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code a, special-care code b
- Treatment state
- any treatment state
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Ammolite, p.33; §6.2 a, b (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Ammolite — care (re-cutting): Stones with superficial colour and surface layers are not suitable for re-cutting or re-polishing.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code m
- Treatment state
- treated
- Only after these treatments
- impregnation
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Ammolite, p.33; §6.2 m (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Ammolite — care (special care): capped with a colourless layer (usually quartz) bonded with UV epoxy for durability: special care (SC); avoid heat and household chemicals.
AGTA Gemstone Information Manual, 17th ed.
- Treatment state
- treated
Source & check 2026-09-26
- Source
- AGTA Gemstone Information Manual, 17th edition (August 2026) (AGTA): p.VII, Gemstone Information Chart, Ammolite ASBL, 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
CleaningFor cleaning, Ammolite in any treatment state must not be cleaned ultrasonically; for chemicals, Ammolite in any treatment state is especially vulnerable to acids and should be kept away from them. For treated Ammolite, and only impregnated material: treatments with dye, oil, resin, wax or plastic are not permanent, so keep it away from all solvents (including dish-washing liquids), chemicals and heat. WearFor wear, Ammolite in any treatment state has low hardness, scratches easily and also breaks easily, so wear it with care; impregnated Ammolite that is surface-coloured or has a surface layer is not suitable for recutting or repolishing. The cleaning, chemicals, wear and recutting conclusions all come from the CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022). AGTAThe AGTA Gemstone Information Manual, 17th edition, records that treated assembled stones, in which a colourless cap (usually colourless quartz) is glued onto the ammonite with UV-curing adhesive to improve durability, need special care (marked SC) and should be kept away from heat and household chemicals.
This table scrolls sideways on narrow screens.
| Question | Matching entries |
|---|---|
| Can it go in an ultrasonic or steam cleaner? | care (cleaning) |
| Contact with acids, alkalis and household chemicals | care (chemicals); Treatments with dye, oil, resin, wax or plastic are not permanent; keep it away from all solvents (including dish-washing liquids), chemicals and heat |
| Wearing limits (knocks, settings) | low hardness, so it scratches easily; wear with care; cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care |
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.
any treatment state
- care (cleaning) §6.2 j
- care (chemicals) §6.2 h
- low hardness, so it scratches easily; wear with care; cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care §6.2 a, b
treated
treated (Only after these treatments: impregnation)
Treatments and identification leads
Registered treatmentsThe registered treatment for Ammolite is impregnation. Stability and frequencyImpregnation has the status treated, its stability is unstable, and it is common on the market. Values not givenIts identification leads and source are both shown as “—”, which, per the registration note, means the cited source gives no value, not “none”.
This table scrolls sideways on narrow screens.
| Treatment | Market frequency (CIBJO) | Stability (CIBJO) | GB/T 16552 category | JJA/AGL listing | Identification leads |
|---|---|---|---|---|---|
| impregnationStatus: treated | commonly | unstable | — | — | — |
Where each treatment acts (schematics): Impregnated
“—” means the cited source gives no value for that item, not “none”. Source: CIBJO Gemstone Book 2022
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 Ammolite, the name register records "Ammonite" and "Ammonite Shell", for which no restriction on use as a name is recorded (CIBJO Gemstone Book 2022 Annex 8 “Ammonite”; CIBJO Gemstone Book 2022 Annex 8 “Ammonite Shell”).
Standard and listing namesThe suggested listing name for Ammolite is "Ammolite". Under GB/T 16552—2017, Ammolite is a mineral or material name that can be used directly; Annex A of GB/T 16552—2017 does not list this material. Names in four languagesThe four-language names cover Simplified Chinese, Traditional Chinese, English (Ammolite) and Japanese; the Japanese name is the entry's own, and the GSJ (Japan) wording for it has not yet been verified by this site. Trade and mineralogical namesThe mineralogical name is given in English as iridescent ammonite fossil shell material. Institution usageOn authority wording, CIBJO lists Ammolite (CIBJO Gemmological Laboratories Book 2024); the FTC text has no wording for Ammolite, and this has been checked; GIA and Gem-A have not yet been checked. Where a body's wording is not recorded or not checked, the English name shown comes from the entry itself and does not represent that body's position. Trade and mineralogical namesAmmonite and Ammonite Shell are English market names that are matched to Ammolite only after conditions are confirmed, with no registered restriction on their use as names.
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) | ||||
| AmmoniteEnglish | market name | matched only once the condition is confirmed | no restriction recorded | CIBJO Gemstone Book 2022 Annex 8 “Ammonite”; CIBJO Gemstone Book 2022 Annex 8 “Ammonite Shell” |
| Ammonite ShellEnglish | market name | matched only once the condition is confirmed | no restriction recorded | CIBJO Gemstone Book 2022 Annex 8 “Ammonite Shell” |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- アンモライト (not yet checked for this body — the entry's own Japanese name is shown)
- Mineral / material name (not in GB/T 16552 Annex A; usable directly)
- 斑彩石 (GB/T 16552—2017 §5.1.1 b))
- Mineralogical name
- Iridescent ammonite fossil shell material
- Trade names and synonyms
- Ammonite (market name; conditional name) · Ammonite Shell (market name; conditional name)
Four-language names
- 简体中文
- 斑彩石
- 繁體中文
- 斑彩石
- English
- Ammolite
- 日本語
- アンモライト
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Fossil and mineralized materials
- Identity tier
- Rock / mineral aggregate
- Mineral chemical class
- Mixed / composition-dependent
- Construction or treatment status
- Natural identity; treatment status unknown
What it is and how it's identified
Among the registered material facts for Ammolite, the treatment recorded under durability is impregnation, with the status treated and the stability of the impregnation effect marked unstable; this site notes that what is judged is the stability of the impregnation treatment's effect, not the durability of ammolite itself, and a complete durability conclusion cannot be assembled. Optically, the registered finding for ammolite is iridescence, and the cited source states that iridescence commonly occurs.
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”.
Durability
For Ammolite, the stability of impregnation is “unstable”.
CIBJO Gemstone Book 2022
- Treatment state
- treated
- Treatment
- impregnation
- Qualification
This says how well the treatment holds up, not how durable Ammolite itself is.
- General note
- no durability verdict here
Source & check 2026-09-25
- Source
- Fact checked on
- 2026-09-25
Optical
Ammolite — optical effect (iridescence): iridescent.
CIBJO Gemmological Laboratories Book 2024
- Qualification
The cited source states that this effect often occurs.
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Testing and market
For identifying Ammolite, the laboratory protocol in the CIBJO Gemmological Laboratories Book 2024 requires checks focused on coating and impregnation. Treated Ammolite (meaning impregnated) is reported as “common” in trade. Which tests the CIBJO laboratory protocol requires for Ammolite, and what each method means, 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: §6.1.4.
How far testing can go
For Ammolite in trade, the reported frequency of impregnation is “commonly”.
CIBJO Gemstone Book 2022
- Treatment state
- treated
- Treatment
- impregnation
Source & check 2026-09-25
- Source
- Fact checked on
- 2026-09-25
Ammolite — what the CIBJO laboratory protocol says to watch for: coating, impregnation
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
Ammolite is defined directly in CIBJO Gemmological Laboratories Book 2024 under the entry name Ammolite. The definition states that the mineral species is mainly aragonite, possibly also containing pyrite and calcite; the rock is fossil ammonite usually found on a schist or limestone matrix; the trade name is Ammolite, with the CIBJO wording quoted in full under Clause-level definitions on this page. The cross-check result is that it is defined directly by CIBJO, and no identically named English entry was found in this edition of the GB/T annex.
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Ammolite | 7.2.1.12 | Pseudomorph after the ammonite shell, often shows iridescent colours | 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
- 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.
- RRUFF Project, in partnership with the IMA – International Mineralogical Association. IMA Mineral List.
- Geological Survey of Japan, AIST (Japan). Museum mineral specimens, browse by classification.
- 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.
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Fossil and mineralized materials | Live |
| Treatments recorded for this material | Impregnated | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Ammolite 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.