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
Eye Agate
Banded chalcedony with concentric, eye-like patterns; "eye" (literally "heavenly eye") is a pattern name with no standing as a separate mineral. 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 Eye Agate 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 Eye AgateIdentification points from the research literature; how far lab testing can go
- Treatments and enhancements of Eye AgateThe enhancements and treatments the GB/T and JJA/AGL tables list
- Hardness, density and refractive index of Eye AgateEach value with its source and check date
- Eye Agate 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 Eye AgateThe 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
Eye agate is a trade name for banded chalcedony (agate) with a concentric 'eye' pattern, and that pattern is the direct expression of the prevailing agate genesis: voids in the rock are filled cyclically from the rim toward the centre by silica-rich fluids, the silica precipitating layer by layer as fibrous microcrystalline quartz into concentric bands that form the 'eye'. Some specimens are monocentric, with a void in the centre or a fill of the youngest generation of silica polymorph. The number, width and pattern of the concentric bands depend on the silica concentration in the fluids plus temperature, pressure and the timing of fluid influxes; Fe, Ti and Mn and Fe compounds determine the colour of each band. The 'eye' pattern is a record of growth, not an artificial or biological feature.
Scope: Used to explain the concentric "eye" patterns of eye agate as a record of the cyclical filling growth of banded chalcedony from the margin towards the centre, and the elemental sources of colour in the rings.
Sources G&G Fall 2013
Where it forms
Voids and vesicles in volcanic rock (geodes, vugs) and fissures in sedimentary rocks, where silica-rich fluids fill them cyclically to form concentric bands.
Sources G&G Fall 2013
Fluid settings bearing Fe, Ti and Mn, which together with Fe compounds determine the colour of the individual bands.
Sources G&G Fall 2013
How it forms, step by step
Silica-rich fluids reach the void via infiltration canals or microfissures.
Fluids circulate from the rim toward the centre, precipitating silica layer by layer as fibrous microcrystalline quartz (chalcedony) into concentric bands — the 'eye' pattern.
The number, width and pattern of the concentric bands depend on silica concentration, temperature, pressure and the timing of fluid influxes.
Band colours are set by Fe, Ti and Mn along with Fe compounds; the centre may stay empty or be occupied by the youngest silica polymorph generation.
Link to appearance
A concentric 'eye' pattern made of multiple bands around a centre, which may be hollow (a vug) or filled with later silica; individual bands differ in colour.
Sources G&G Fall 2013
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
Related base materials
- Agate: pattern form | Eye agate is banded chalcedony (agate) with concentric 'eye' patterns
- Chalcedony: mineral-base | Composed of microcrystalline quartz (chalcedony)
Supporting findings
Eye agate's concentric 'eye' pattern records the cyclic rim-to-centre filling and layer-by-layer precipitation that forms banded chalcedony.
Evidence grade AScope: Based on the prevailing banded-chalcedony hypothesis; the specific definition of the trade name 'eye agate' is not given in the cited source.
The number, width and pattern of the concentric bands depend on silica concentration plus temperature, pressure and the timing of fluid influxes.
Evidence grade AScope: The prevailing hypothesis for banded chalcedony; the precise banding mechanism is still debated.
Banded chalcedony (including eye agate) occurs in voids or fissures in various volcanic and sedimentary rocks; some specimens are monocentric with a hollow centre.
Evidence grade AScope: Based on agate in general; host rocks and scale differ between localities.
Causes of colour and optical effects
Band colours are determined by Fe, Ti and Mn, and red-brown bands are coloured by Fe compounds such as hematite.
Evidence grade AScope: Concerns Fe-bearing red bands; colourless/grey-white bands follow other mechanisms.
How it is identified
For eye agate, 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
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The authoritative source discusses concentric/banded chalcedony collectively as 'agate' and does not define the pattern trade name 'eye agate'.
- The precise banding mechanism forming the 'eye' pattern is still not fully understood.
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
- Eye Agate
GB/T 16552—2017 5.1.1 c)
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Heated / Heat-treated (via parent material), Filled / Fracture-filled (via parent material), Dyed (via parent material)
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
"Eye Agate" is a market name rather than a mineral species name; before using it, verify: Industry-wide term that does not denote a single species.
What this means for you
Before buying, check the recommended listing name "Eye Agate" 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
- Industry-wide term that does not denote a single species.
- Suggested listing name
- Eye Agate
Care and wear
No care facts are recorded for this entry itself. Its parent material has care records: see Quartz.
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 | — | — |
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16552—2017 Table B.1 (row for Chalcedony)
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 Eye Agate, the name register records "Eye agate", for which no restriction on use as a name is recorded.
Names in four languagesThe four-language names for Eye Agate are the Simplified Chinese name, the Traditional Chinese name, the English name Eye Agate and the Japanese name; the trade name and synonym is Eye agate. Trade and mineralogical namesMineralogically it is described as banded chalcedony with a concentric eye pattern, and its identity level is a trade name (a colour or appearance variety). Standard and listing namesGB/T 16552—2017 does not list this name; the corresponding name in the standard is agate. The suggested listing name is eye-pattern agate. Japanese namesFor Japan, the entry's own Japanese name is shown, and the wording of GSJ (Japan) for this name is not yet verified by this site. Institution usageOn the wording of outside bodies, the FTC and CIBJO texts on file have no wording for this name (checked), and GIA and Gem-A are unchecked; bodies without a recorded wording show the entry's own English name, Eye Agate, 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) | ||||
| Eye agateEnglish | 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
- アイアゲート／天眼瑪瑙 (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)
- 玛瑙 (GB/T 16552—2017 §5.1.1 c))
- Mineralogical name
- Banded chalcedony with concentric eye pattern
Four-language names
- 简体中文
- 天眼玛瑙
- 繁體中文
- 天眼瑪瑙
- English
- Eye Agate
- 日本語
- アイアゲート／天眼瑪瑙
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
The optimization and treatment mapping for Eye Agate is applied by this site from the “Chalcedony (agate/jasper)” content of GB/T 16552—2017 Annex B, Table B.1; GB/T 16552—2017 itself does not register Eye Agate. As applied, heating is classed as optimization, dyeing as optimization, and filling is classed according to its grades. What Table B.1 notes and how the filling grades are defined are explained on this site's Gem treatments page, and the full content including the effect column is on the Chalcedony entry.
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.
What it is and how it's identified
The material and identification facts for Eye Agate are recorded under the GB/T 16553—2017 clause for chalcedony (including agate and jasper, the whole class), not measured for Eye Agate on its own. For that whole class, Eye Agate has a structure (overall) of a cryptocrystalline aggregate, dense and massive, and may also form spherulitic, radial or finely fibrous aggregates; Mohs hardness 5–7; cleavage none; density 2.5–2.77 g/cm³; optic character anisotropic aggregate; refractive index 1.535–1.539, and this site notes that the cited clause has finer ranges and the overall value is used; birefringence not measurable on an aggregate; pleochroism not measurable on an aggregate when untreated; the optical effects iridescence and chatoyancy may be seen; and lustre (as a quality factor) is vitreous to greasy when untreated. Chemical composition, fluorescence, UV-visible spectrum, infrared spectrum and magnification are recorded under the clause for the whole class; see 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 Eye Agate 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 Eye Agate (how to read class-level values).
Structure
Eye Agate — 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
Eye Agate — 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
Eye Agate — 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
Eye Agate — 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
Eye Agate — 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
Eye Agate — 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
Eye Agate — 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
Eye Agate — 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
Eye Agate — 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
Eye Agate — 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
Eye Agate — 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 Eye Agate 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.
Evidence and sources
Authority basis and clause sources
Sources
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 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 (Eye Agate) 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
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Quartz and chalcedony materials | Live |
| Treatments recorded for this material | Heated / Heat-treated (via parent material), Filled / Fracture-filled (via parent material), Dyed (via parent material) | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Eye Agate 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.