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Natural inorganic gem materials · Mineral / gemstone variety · Natural identity; treatment status unknown

Clear Quartz / Rock Crystal

Also known asRock crystal

The colorless transparent variety of quartz, whose GB/T basic name is "Rock Crystal"; irradiation or heating can change its color. 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.

Edited by RalphReviewed by JuneLast updated 2026-10-12Who maintains this page

FAQ

Questions people ask about Clear Quartz / Rock Crystal

Every sentence below is followed by the registered fact it rests on; answers add no new facts and promise no outcome.

Q1How can you tell if clear quartz is real, synthetic or glass?

According to the parent entry Quartz, colour and appearance do not prove whether a quartz is natural or synthetic; laboratories combine twinning and colour zoning seen under the microscope with chemical analysis such as EDXRF and infrared spectroscopy.G&G Summer 2014 · CIBJO Gemstone Book 2022 (via parent entry Quartz)Its refractive index is recorded as 1.544–1.553.GB/T 16553—2017Its density is recorded as 2.64–2.69 g/cm³.GB/T 16553—2017Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.What this page can answer

Q2What is clear quartz, and is it the same as rock crystal?

Yes: rock crystal is the transparent, colourless variety of quartz, SiO2, a variety of the quartz species rather than a separate mineral.G&G Fall 2024It is colourless because the crystal lacks colour-causing impurities or colour centres, which is what separates it from amethyst, rose quartz and smoky quartz.G&G Fall 2024

Q3Is clear quartz durable enough to wear every day?

Its hardness is recorded as Mohs 7.GB/T 16553—2017For transparent quartz, the parent entry Quartz records prong and bezel settings as relatively safe and flush, channel and pavé as best avoided, noting that stones may be included or fractured.Gems & Gemology 1987 (Martin) (via parent entry Quartz)The Quartz record also advises avoiding thermal shock, which may fracture it.Gems & Gemology 1987 (Martin) (via parent entry Quartz)

Q4How should clear quartz be cleaned?

For transparent quartz, the parent entry Quartz records that ultrasonic and steam cleaning call for caution and thermal shock should be avoided.Gems & Gemology 1987 (Martin) (via parent entry Quartz)

Q5Is it safe to leave clear quartz in the sun?

For transparent quartz other than amethyst and citrine, the parent entry Quartz rates display-case heat, sunlight and artificial light as relatively safe.Gems & Gemology 1987 (Martin) (via parent entry Quartz)

Q6How does clear quartz form?

Silica carried by migrating solutions can build up slowly inside cavities and gas bubbles in rock and deposit quartz there.G&G Spring 1982Quartz crystals commonly grow inward from the walls of open cavities, forming clusters called druses.G&G Spring 2017

Q7What does clear quartz symbolize, and does it have healing powers?

There is no scientific evidence that clear quartz 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)As a birthstone, the U.K. National Association of Jewellers lists it as an alternative for April.Cultural recordsMuseum collections show rock crystal beads going back at least to the late 8th millennium BCE in Syria, and later in Minoan Crete and the Roman world.The Met 1985.356.72 · The Met 26.31.403 +4

Q8What makes good-quality clear quartz?

Rock crystal has long been valued for its clarity; collectors seek artistically carved pieces, modern and antique, and connoisseurs of inclusions collect cut rock crystal with mineral inclusions.CIBJO Retailers' Reference Guide (2021)

What this page can answer

This page covers

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

Rock crystal (white quartz) is the transparent, colorless variety of quartz (SiO2) — a variety of the quartz mineral species, not a separate mineral. Natural quartz crystals commonly grow inward from the walls of open cavities, vesicles and vugs out of silica-rich fluid, as dissolved silica accumulates slowly from migrating solutions; colorless quartz appears where the trace impurities or colour centres that tint other quartz varieties are absent, so it can occur alongside coloured varieties such as amethyst in the same mineralizing system.

Scope: Covers the formation environment of natural colourless quartz (rock crystal) and its status as "colourless"; does not cover synthetic quartz, glass imitations or artificially colour-altered material.

Sources G&G Fall 2024 · G&G Spring 2017 · G&G Spring 1982

Where it forms

Cavities and vesicles in rock where silica-bearing fluid deposits quartz, the silica accumulating slowly from migrating solutions.

Sources G&G Spring 1982 · G&G Spring 2017

Open vugs where quartz crystals grow inward from the walls out of silica-rich fluid, forming druses.

Sources G&G Spring 2017 · G&G Fall 2024

Mineralizing systems shared with other quartz varieties: colorless quartz can occur alongside amethyst and citrine in the same vug.

Sources G&G Fall 2024

How it forms, step by step

  1. Silica-bearing fluid enters cavities, vesicles or vugs in the rock.

    Sources G&G Spring 1982 · G&G Spring 2017

  2. Dissolved silica accumulates slowly from migrating solutions and precipitates in open spaces, crystallizing inward from the walls.

    Sources G&G Spring 1982 · G&G Spring 2017

  3. Where colour-causing impurities or colour centres are absent, the quartz crystallizes as transparent, colorless rock crystal.

    Sources G&G Fall 2024

  4. Within one mineralizing system, colorless quartz and coloured varieties such as amethyst and citrine may crystallize together or in sequence.

    Sources G&G Fall 2024

Link to appearance

The crystal lacks colour-causing impurities or colour centres, so it is transparent and colorless; this high transparency and absence of body colour distinguish rock crystal from coloured varieties such as amethyst, rose quartz and smoky quartz.

Sources G&G Fall 2024

Timescale

The sources mention a geologic time span for natural irradiation but give no absolute age or duration for growth of colorless quartz itself; that span is not tied to the colorlessness of rock crystal, so no time claim is made here.

Sources G&G Fall 2024

Related base materials

  • Quartz (SiO2): variety-of | Clear quartz is the transparent, colourless variety of quartz

Supporting findings

Silica delivered by migrating solutions can accumulate slowly inside cavities and vesicles, depositing quartz there.

Evidence grade A

Scope: The source describes amethyst/citrine/green-quartz clusters north of Reno on the California-Nevada border; the deposition mechanism is analogous to quartz generally but is not specific to rock crystal.

Sources G&G Spring 1982

Quartz crystals commonly grow inward from the walls of open vugs out of silica-rich fluid, forming druses.

Evidence grade A

Scope: The source is a quartz druse in Deccan Trap basalt vugs in India; a general quartz occurrence setting.

Sources G&G Spring 2017

Colorless quartz can occur together with coloured quartz varieties in the same mineralizing system, as with colorless quartz crystals and colorless outer zones in amethyst pockets.

Evidence grade A

Scope: The source is the La Manche amethyst deposit, Canada, referring to colorless growth portions of quartz rather than material traded specifically as rock crystal.

Sources G&G Fall 2024

Recorded localities

Authoritative sources list the localities below; the list is not exhaustive.

Locality sketch mapLand outlines only; the map does not depict any national or regional boundary. Dots mark approximate positions. Base map: Natural Earth (public domain).

Africa

  • MadagascarMineral specimen locality (not a source of jewellery material)
    Sources Handbook of Mineralogy

Europe

  • Alps, Switzerland and AustriaMineral specimen locality (not a source of jewellery material)Fine specimens from many places in the Swiss and Austrian Alps
    Sources Handbook of Mineralogy

North America

  • Mt. Ida to Hot Springs, Ouachita Mountains, Arkansas, United StatesMineral specimen locality (not a source of jewellery material)
    Sources Handbook of Mineralogy

South America

  • Rio Grande do Sul, Minas Gerais, Goiás and Bahia, BrazilMineral specimen locality (not a source of jewellery material)
    Sources Handbook of Mineralogy

Seas and coasts

  • WorldwideMineral specimen locality (not a source of jewellery material) · not on the mapQuartz as a species is extraordinarily common
    Sources Handbook of Mineralogy

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.

Human use and museum objects

On the museum evidence, the use of rock crystal as beadwork reaches back at least to about the late 8th millennium BCE (Met 1985.356.72, Syria), and is later seen in Minoan beads (26.31.403, 26.31.404) and in objects from the Roman world, Cyprus and Japan (e.g. 74.51.3600, 2000.1, 12.37.33).

Evidence grade A

Scope: Applies to collection objects recorded as rock crystal (colourless transparent quartz variety); other quartz varieties are not covered.

Sources The Met 1985.356.72 · The Met 26.31.403 · The Met 26.31.404 +3

The Met holds a rock-crystal bead dated to about the late 8th millennium BCE (Neolithic; acc. 1985.356.72, Syria), among the earliest crystal beads in its collection. Minoan Crete also left rock-crystal beads (acc. 26.31.403 striated bead; 26.31.404 figure-of-eight shield bead; ca. 2200-1450 BCE). Crystal was later worked into objects: Cypriot or Phoenician bottles (acc. 74.51.3600, 74.51.3599, ca. 5th-2nd century BCE), a Roman rock-crystal-and-silver spoon (acc. 2000.1, first half of the 1st century CE) and a gold earring with a crystal bead (acc. 74.51.3619, 1st-2nd century CE). East Asian examples exist too, e.g. a Japanese crystal bead of the 7th century or earlier (acc. 12.37.33). Rock crystal is the colourless transparent variety of quartz; the evidence pertains to that parent material.

Sources The Met 1985.356.72 · The Met 26.31.403 · The Met 26.31.404 +3

Scope: A museum object evidences only the existence and date of that artefact itself; it does not establish widespread ancient use of the material, nor does it attest the origin, naturalness, or treatment of any modern specimen.

Objects cited

8000 BCE6000 BCE4000 BCE2000 BCE02000Met 1985.356.72ca. late 8th millennium BCEMet 26.31.403ca. 2200–1450 BCEMet 26.31.404ca. 2200–1450 BCEMet 74.51.3600ca. 5th–2nd century BCEMet 2000.11st half of 1st century CE
Dates of museum objectsDates from the museums' open-access records (CC0); each bar spans the whole period named in the record, with qualifiers such as “early” or “possibly” kept in the label rather than turned into a narrower range; an arrow marks a record that reads “before” or “after” a yearSource: The Met / Cleveland Museum of Art open-access records
  • The Met 1985.356.72Bead · ca. late 8th millennium BCE · SyriaRock crystal
  • The Met 26.31.403Rock crystal bead with striations · ca. 2200–1450 BCE · MinoanRock crystal
  • The Met 26.31.404Rock crystal bead in the form of a figure-of-eight shield · ca. 2200–1450 BCE · MinoanRock Crystal
  • The Met 74.51.3600Rock crystal bottle · ca. 5th–2nd century BCE · Cypriot or PhoenicianRock crystal
  • The Met 2000.1Rock-crystal and silver spoon · 1st half of 1st century CE · RomanRock crystal and silver
  • The Met 12.37.33Bead · 7th century or earlier · JapanRock crystal

Cultural records for this material: Birthstone list.

How it is identified

For rock crystal (colourless quartz), 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 A

Scope: 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

Rock crystal is the transparent, colorless variety of quartz (SiO2), a variety of the quartz species rather than a separate mineral, distinguished by its lack of body colour from coloured varieties such as amethyst and smoky quartz.

Evidence grade B

Scope: The source describes rock crystal via colorless quartz spheres and does not give a formal definition of the colorless variety; the boundary here is drawn from varietal relationships.

Sources G&G Fall 2024

Rock crystal has long been cherished for its clarity; among collectors, artistically carved rock crystal, both modern and antique, is desirable, and connoisseurs of inclusions collect cut rock crystal with mineral inclusions.

Evidence grade B

Scope: What collectors favour, as described in a trade association's reference guide; not a grading standard and not a statement about the value of any piece.

Sources CIBJO Retailers' Reference Guide (2021)

Limits of this research

  • Research status: Formation, occurrence or other material-specific findings found in authoritative sources
  • No source states directly that colorless quartz is colorless because it lacks colour-causing impurities/colour centres; this is inferred by contrast with the colour mechanisms of coloured varieties.
  • The quartz settings cited (basalt vugs, the La Manche vein) are not specific to rock-crystal localities.

Methodology

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
Clear Quartz / Rock Crystal

GB/T 16552—2017 Table A.1 “Rock Crystal”, 5.1.1 a) · CIBJO Gemmological Laboratories Book 2024 §7.2.1.198 “Rock crystal”

Construction or treatment status

Natural identity; treatment status unknown

Treatments recorded for this material: Heated / Heat-treated (via parent material), Irradiated (via parent material), Filled / Fracture-filled (via parent material), Dyed (via parent material), Coated (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

The Chinese standard lists Clear Quartz / Rock Crystal under a different Chinese name from its common trade name (GB/T 16552—2017 Table A.1); use "Clear Quartz / Rock Crystal" for listings.

What this means for you

Before buying, check the recommended listing name "Clear Quartz / Rock Crystal" 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

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.

TreatmentMarket frequency (CIBJO)Stability (CIBJO)GB/T 16552 categoryJJA/AGL listingIdentification leads
Heating——Optimization——
Irradiation——Optimization——
Filling——Graded — see §5.4.1, Table 1——
Dyeing——Treatment——
Coating——Treatment——

“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16552—2017 Table B.1 (row for Rock Crystal); 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 Clear Quartz / Rock Crystal, the name register records "Rock crystal", for which no restriction on use as a name is recorded; 2 further names in non-Latin scripts are listed in the name register below (2 with no restriction recorded on use as a name).

Standard and listing namesThe Chinese formal name for Clear Quartz / Rock Crystal is rock crystal (GB/T 16552—2017 Table A.1); the Chinese market name, meaning "white crystal/quartz", is registered as a single name and is not split at the slash. The suggested listing name is "Clear Quartz". Trade and mineralogical namesThe mineralogical name is Quartz (SiO2), colorless variety, and the trade name and synonym is Rock crystal. Names in four languagesThe names cover Simplified Chinese, Traditional Chinese, English (Clear Quartz / Rock Crystal) and Japanese; the GSJ (Japan) formal name is the Japanese term for crystal. Candidate search termsThe JJA/AGL gem name handbook 2025 (p.10) also registers a Japanese transliteration of rock crystal, which serves only as a candidate search term. National standard namesGermany (RAL) writes Bergkristall and the EU writes Rock Crystal. Institution usageThis site has not yet verified the wording of GIA, FTC, CIBJO or Gem-A for this material; the entry's own English name is Clear Quartz / Rock Crystal, which does not represent the position of GIA, FTC, CIBJO or Gem-A.

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.

NameTypeMatchingUse as a nameBasis
no restriction recorded (3)
Rock crystalEnglishsynonymmatched automaticallyno restriction recordededitorial ruling (no clause cited)
ロック・クリスタルJapanesetransliterationsearch candidate onlyno restriction recordedJJA/AGL Gemstone Nomenclature 2025 p.10
白水晶/石英Simplified Chinesemarket namematched automaticallyno restriction recordededitorial ruling (no clause cited); Note: Product name with a slash pair; the whole string is registered as one name (Chinese names are not split at the slash).

How each authority words this name: see Names › Authority wording.

Authority wording

GIA, FTC, CIBJO, Gem-A
Clear Quartz / Rock Crystal (not yet checked by this site — the entry's own English name is shown)
GSJ (Japan) formal name
クリスタル／水晶
Chinese formal name
水晶 (GB/T 16552—2017 Table A.1)
Mineralogical name
Quartz (SiO2), colorless variety
Trade names and synonyms
Rock crystal (synonym)

Four-language names

简体中文
白水晶
繁體中文
白水晶
English
Clear Quartz / Rock Crystal
日本語
クリアクォーツ／水晶

National and regional formal names

Germany (RAL)
Bergkristall
European Union
Rock Crystal

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
Mineral / gemstone 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 “Rock Crystal” row of Table B.1: Heating Optimization; Irradiation Optimization; Filling Graded — see §5.4.1, Table 1; Dyeing Treatment; Coating Treatment. The full row, with the effect column, is on the Rock Crystal 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 nameSpeciesColourListed in the tableNotes
Rock CrystalQuartzcolourlessan untreated tier is listed

JJA/AGL definitions and nomenclature (2025 revision), table of principal gem names, p.10

How to read the JJA/AGL table: see the Gem treatments page.

What it is and how it's identified

The material facts for Clear Quartz / Rock Crystal are written in the cited standard for rock crystal (the whole class), not measured for Clear Quartz / Rock Crystal on its own; chemical composition, fluorescence, UV-visible spectrum, infrared spectrum and magnification are given for the whole class on the Rock Crystal entry. For the whole class, the structure is crystalline, trigonal, with hexagonal prismatic crystals bearing distinct horizontal striations on the prism faces; Mohs hardness is 7 and cleavage none. For the whole class, density is 2.64–2.69 g/cm³; the cited clause gives 2.66 with tolerance (+0.03/−0.02), from which the limits are derived. For the whole class, optic character is anisotropic, uniaxial, positive, and a bull's-eye interference figure may appear; refractive index is 1.544–1.553 and birefringence 0.009. As optical effects for the whole class, chatoyancy may be seen, as may asterism, a six-rayed star mostly found in rose quartz. When untreated, for the whole class, pleochroism is weak and varies with colour, and lustre (as a quality factor) is vitreous.

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 rock crystal (the whole class), so they are not repeated on the Clear Quartz / Rock Crystal page; see the material facts on the Rock Crystal entry.

Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Clear Quartz / Rock Crystal (how to read class-level values).

Structure

Clear Quartz / Rock Crystal — structure (overall): crystalline

GB/T 16553—2017

Does this standard apply
applies to this entry
What this covers
rock crystal (the whole class)
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Clear Quartz / Rock Crystal — structure (crystal system): trigonal

GB/T 16553—2017

Does this standard apply
applies to this entry
What this covers
rock crystal (the whole class)
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Clear Quartz / Rock Crystal — structure (crystal habit): hexagonal prisms with prominent horizontal striations on the prism faces

GB/T 16553—2017

Does this standard apply
applies to this entry
What this covers
rock crystal (the whole class)
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Durability

Clear Quartz / Rock Crystal — Mohs hardness: 7

GB/T 16553—2017

123456789107References (diamond = value, bar = range; below)

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))

Mohs hardnessSource: GB/T 16553—2017
Does this standard apply
applies to this entry
What this covers
rock crystal (the whole class)
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Clear Quartz / Rock Crystal — cleavage: none

GB/T 16553—2017

Does this standard apply
applies to this entry
What this covers
rock crystal (the whole class)
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Physical properties

Clear Quartz / Rock Crystal — density: 2.64–2.69 g/cm³

GB/T 16553—2017

0.51.52.53.54.55.56.57.52.64–2.69
Specific gravitySource: GB/T 16553—2017
Does this standard apply
applies to this entry
What this covers
rock crystal (the whole class)
Qualification

The clause we cite gives 2.66, with a stated tolerance of +0.03 / -0.02. The range shown here is worked out from that.

Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Optical

Optical effects on record: chatoyancyrepresentative example: cause in Tiger’s Eye (schematic)asterismrepresentative example: cause in Star Sapphire (schematic)

Clear Quartz / Rock Crystal — optic character: anisotropic material, uniaxial, with positive optic character; a “Bull's eye” interference figure may be present, and Brazil-law twinning is common in amethyst.

GB/T 16553—2017

Does this standard apply
applies to this entry
What this covers
rock crystal (the whole class)
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Clear Quartz / Rock Crystal — refractive index: 1.544–1.553

GB/T 16553—2017

1.31.72.12.52.93.31.544–1.553
Refractive indexSource: GB/T 16553—2017
Does this standard apply
applies to this entry
What this covers
rock crystal (the whole class)
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Clear Quartz / Rock Crystal — birefringence: 0.009

GB/T 16553—2017

00.050.10.150.20.250.30.009
BirefringenceSource: GB/T 16553—2017
Does this standard apply
applies to this entry
What this covers
rock crystal (the whole class)
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Clear Quartz / Rock Crystal — pleochroism: weak; it depends on the body colour.

GB/T 16553—2017

Treatment state
untreated
Does this standard apply
applies to this entry
What this covers
rock crystal (the whole class)
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Clear Quartz / Rock Crystal — optical effect (chatoyancy): seen

GB/T 16553—2017

Does this standard apply
applies to this entry
What this covers
rock crystal (the whole class)
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Clear Quartz / Rock Crystal — optical effect (asterism): seen; a six-rayed star, common in rose quartz.

GB/T 16553—2017

Does this standard apply
applies to this entry
What this covers
rock crystal (the whole class)
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
Fact checked on
2026-09-26
CIBJO definitions
chatoyancy, asterism

Quality factors

Clear Quartz / Rock Crystal — quality factor (lustre): vitreous

GB/T 16553—2017

Treatment state
untreated
Does this standard apply
applies to this entry
What this covers
rock crystal (the whole class)
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (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.

1.531.541.551.561.571.582.52.62.72.82.9Refractive indexSpecific gravity12345Clear Quartz / Rock Crys…

This material (RI / SG midpoints): 1.548 / 2.67; Closest values: 1Agate 1.537 / 2.63, 2Shoushan Stone 1.56 / 2.7, 3Changhua Stone 1.56 / 2.6, 4Bamboo Coral 1.57 / 2.65, 5Synthetic Beryl 1.57 / 2.69

Show the full chart (330 registered materials)1.41.51.61.71.81.922.12.22.32.41234567Refractive indexSpecific gravity12345Clear Quartz / Rock Crystal

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

Refractive index × specific gravity (all registered materials)Each dot is one material's registered refractive index and specific gravity (range midpoints, not measurements); gold = this material, dark = the nearest few (picked on this site by distance in RI ÷ 0.02 and SG ÷ 0.1, leaving out near-identical varieties of the same species)Source: each material's registered refractive index and specific gravity facts (GB/T 16553 and others; sources on each entry)

Testing and market

The CIBJO laboratory protocol covers Clear Quartz / Rock Crystal under “Quartz” (§6.1.65): see identification on the Quartz entry; the required tests are listed on the CIBJO laboratory protocol table for Quartz.

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

Clear Quartz / Rock Crystal has a clause-level definition in the CIBJO Gemmological Laboratories Book 2024, under the entry name Rock crystal, defined as a colourless, transparent variety of quartz. Cross-check result: defined directly by CIBJO; also present in the GB/T 16552—2017 annex.

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TermClauseDefinitionCross-check
Rock crystal7.2.1.198Colourless, transparent variety of quartzDefined directly by CIBJO; also present in the GB/T annex.

Evidence and sources

Authority basis and clause sources

GB/T 16552—2017
Listed Table A.1 “Rock Crystal” · Source
GB/T 16552—2017
Naming rule 5.1.1 a) · Source
CIBJO Gemmological Laboratories Book 2024
Listed §7.2.1.198 “Rock crystal” · Source

Sources

Further reading

Related pages

Treatments recorded for this material

Recorded cultural contexts

Birthstone list

The U.K. National Association of Jewellers chart lists Clear Quartz / Rock Crystal as an alternative for April. This records trade-association convention only; it does not establish material identity, natural origin, treatment, provenance, or effect.

Relation
Industry list inclusion

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Publisher or holderRegionFrom / periodSource and locator
National Association of JewellersUnited Kingdom—National Association of Jewellers, “Zodiac Birthstones Jewellery: Star Signs, Gemstones and Their Meaning” (web page, consulted 2026-08-22)
Zodiac birthstone chart, April row: Clear Quartz / Rock Crystal (Alternative)

Related intention themes

These reviewed links connect this material with LumaLark intention themes. Each label identifies whether the link is a brand interpretation or a historical and cultural record; neither describes an effect or outcome of the material.

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 (Clear Quartz / Rock Crystal) is marked.

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PageContentStatus
Browsing familyQuartz and chalcedony materialsLive
Treatments recorded for this materialHeated / Heat-treated (via parent material), Irradiated (via parent material), Filled / Fracture-filled (via parent material), Dyed (via parent material), Coated (via parent material)Live
Related articlesTo be added (placeholder)Planned

Who maintains this page

The material facts in the Clear Quartz / Rock Crystal 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.

Facts editor
Ralph
Reviewer
June
How facts are checked
Each fact is matched to the clause it cites; facts checked on 2026-09-26
Last revised
2026-10-12
Purpose
Lets buyers and sellers check naming, disclosure and material facts clause by clause.

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