Key properties
| Chemical formula | Al2SiO4(F,OH)2 |
| Crystal system | Orthorhombic |
| Mohs hardness | 8 |
| Toughness | Poor - one perfect cleavage direction makes stones vulnerable to knocks and thermal shock |
| Refractive index | 1.619-1.627 |
| Birefringence | 0.0080-0.0100 |
| Optic character | Biaxial positive (DR) (+) |
| Dispersion | 0.0140 |
| Specific gravity | 3.49-3.57 |
| Cleavage | Perfect basal cleavage parallel to the base of the crystal ({001}) |
| Fracture | Conchoidal to uneven |
| Habit | Prismatic orthorhombic crystals with wedge-shaped terminations, often large and well-formed |
| Lustre | Vitreous; polish: Vitreous |
| UV fluorescence | Yellow to brown and pink to red stones often glow weak to moderate orange-yellow in long-wave (weaker in short-wave); blue and colourless stones inert to weak yellow or green |
| Pleochroism | Weak to moderate by colour: blues show different tones of blue, yellows and browns brownish yellow versus yellow-brown, reds and pinks light red versus orangy red to yellow |
| Cause of colour | Allochromatic: colour centres created by natural (or laboratory) irradiation plus trace chromium for some natural pinks, reds and orange imperial material |
| Typical inclusions | Two- and three-phase cavities containing immiscible (non-mixing) liquids - a classic diagnostic • elongated hollow tubes • fingerprint healing patterns • growth tubes parallel to the c-axis |
| Stability | Stable to light and everyday chemicals • rapid heating or cooling causes internal breaks along cleavage • strong heat can alter or destroy colour • some brown stones slowly fade in light |
| Heat sensitivity | High risk - never steam clean or torch; even warm soapy water should be tepid, not hot |
| Care and cleaning | Warm (never hot) soapy water only • ultrasonic: never • steamer: never • protect stone edges in settings; remove rings for heavy work |
| Birthstones | Topaz is the November birthstone • blue topaz is a December birthstone alternate and marks the 4th wedding anniversary • imperial topaz is associated with the 23rd anniversary |
| Availability | Plentiful overall - irradiated blue dominates the market; natural fine orange, pink and red are limited; natural untreated blue is rare |
| Recognition | RI 1.61-1.63 (typically 1.62) with DR 0.008-0.010, SG about 3.53, hardness 8 and one perfect cleavage; the combination of immiscible-liquid inclusions and basal cleavage is close to diagnostic |
Varieties (5)
Red-Pink Topaz
| Colour | rose pink to red and purplish red, usually light in tone |
| Transparency | transparent |
| Clarity type | Type I - usually eye-clean |
| Phenomena | None |
| Appearance | Soft rose to raspberry red with bright vitreous sparkle; even in fine stones the tone is delicate rather than deep |
| Trade names | Rose topaz • precious topaz (for natural material) |
| Misnomers | 'Brazilian ruby' historically misused for red topaz • irradiated pink sold without treatment disclosure |
| Typical sizes | 1 to 8 ct typical; stones over 10 ct rare |
| Cutting styles | Faceted - ovals, cushions, emerald cuts; orient the table to show the best pleochroic colour |
| Key separations | Vs pink tourmaline: tourmaline RI 1.62-1.64 with much stronger DR (0.014-0.022), different SG (3.05 vs 3.53) • Vs morganite: beryl RI 1.57-1.58, SG 2.80 • Vs pink spinel: singly refractive RI about 1.72 • Vs kunzite: kunzite RI 1.66-1.68, strong pleochroism, fades in light |
| Sources (localities) | Brazil (Ouro Preto region) • Pakistan (Katlung, pink) • Russia (Urals) • Nigeria • Mexico (San Luis Potosi, orangey red) • USA (Utah) • Zimbabwe |
| Availability | Natural red and pink are scarce and prized; treated pink is widely available |
| Market notes | True natural red topaz is a rarity commanding strong premiums; disclose irradiation on treated pinks, which fade rarely but should be tested for stability |
| Care notes | Protect from knocks (cleavage); no ultrasonic or steam; tepid soapy water only |
| In short | Red to pink topaz is delicate rose to raspberry colour, genuinely natural only in small amounts from Brazil, Pakistan and Mexico. Most commercial pink is irradiated material and must be sold as such. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 1.00–5.00 | $20.00 – $150.00 | treated commercial to fine | 2026-10-26 |
| 1.00–5.00 | $200.00 – $1500.00 | natural rare | 2026-10-26 |
Retail market survey, per carat unless noted. Ranges describe what commercial to fine stones trade at; exceptional stones and provenance premiums sit above them.
Blue Topaz
| Colour | very slightly greenish blue to greenish blue and deep steely blue |
| Transparency | transparent |
| Clarity type | Type I - usually eye-clean |
| Phenomena | None |
| Appearance | Clean, bright blue in three familiar trade depths - pale sky blue, medium Swiss blue and dark London blue with a greyish cast |
| Trade names | Sky Blue (pale) • Swiss Blue (medium-electric) • London Blue (dark steely) • Maxi Blue |
| Misnomers | 'Brazilian sapphire' - historic misnomer for blue topaz, it is not sapphire |
| Typical sizes | 5 to 25 ct standard; museum cuts over 100 ct and even 2000 ct exist |
| Cutting styles | Faceted brilliants, ovals, emerald cuts; calibrated sizes dominate |
| Key separations | Vs aquamarine: aqua RI 1.57-1.58, SG 2.72, uniaxial negative • Vs blue zircon: zircon RI over limit, strong doubling, SG about 4.65 • Vs blue tourmaline: stronger DR, different SG and pleochroism • Vs synthetic blue spinel: singly refractive, RI 1.72-1.73, cobalt spectrum |
| Sources (localities) | Nearly all is colourless topaz from Brazil irradiated and heated; other feedstock from Sri Lanka, Nigeria, China and Russia |
| Availability | Plentiful in calibrated sizes |
| Market notes | The workhorse affordable blue; Sky and Swiss dominate bridal-adjacent fashion jewellery, London Blue trades at a premium. Treatment disclosure is mandatory; irradiated material is released only after regulatory decay checks. |
| Care notes | No ultrasonic or steam; tepid soapy water; the colour is stable to light and normal wear |
| In short | Blue topaz is the market's affordable blue faceted stone, made by irradiating and heating colourless topaz into Sky, Swiss and London Blue depths. Clean, bright, calibrated and cheap, it is always a treated product that must be disclosed. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 1.00–10.00 | $5.00 – $40.00 | commercial | 2026-10-26 |
Retail market survey, per carat unless noted. Ranges describe what commercial to fine stones trade at; exceptional stones and provenance premiums sit above them.
Imperial / Golden Topaz
| Colour | sherry orange to reddish orange 'imperial', and golden to champagne yellow |
| Transparency | transparent |
| Clarity type | Type I - usually eye-clean |
| Phenomena | None |
| Appearance | Luminous sherry, peach and reddish orange with bright vitreous lustre; fine imperial shows a medium reddish orange that glows rather than looks brown |
| Trade names | Imperial topaz (fine medium reddish orange, Ouro Preto) • precious topaz (distinguishes topaz from mislabelled quartz) • sherry topaz (brownish yellow to orange) |
| Misnomers | 'Madeira topaz', 'Palmyra topaz', 'Spanish topaz', 'Bohemian topaz' - all citrine quartz, not topaz • 'hyacinth topaz' obsolete |
| Typical sizes | 1 to 8 ct typical; faceted stones over 30 ct rare |
| Cutting styles | Faceted ovals, cushions, emerald cuts; Portuguese cuts show off colour depth |
| Key separations | Vs citrine: quartz RI 1.544-1.553, SG 2.65, weaker lustre • Vs heliodor: beryl RI 1.57-1.58 • Vs hessonite: singly refractive, RI about 1.74, roiled look • Vs spessartite: singly refractive, RI about 1.81, manganese spectrum • RI 1.62 plus SG 3.53 and cleavage confirm topaz |
| Sources (localities) | Brazil (Ouro Preto, Minas Gerais - the imperial topaz type area) • Russia (Urals) • Pakistan • Nigeria • Sri Lanka • USA (Utah) |
| Availability | Fine orange imperial is limited; golden and sherry tones more available but still modest |
| Market notes | The name 'imperial' is stretched over pale golden material by many sellers; true Ouro Preto reddish orange commands collector premiums that rise steeply with size |
| Care notes | Cleavage-prone: no ultrasonic or steam; tepid soapy water; guard ring edges |
| In short | Imperial topaz from Ouro Preto is the species' pinnacle - natural reddish orange with a chromium component, usually untreated. Golden and sherry topaz are its more affordable cousins, constantly mislabelled in the market by citrine sold as 'topaz'. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 1.00–5.00 | $20.00 – $120.00 | golden commercial | 2026-10-26 |
| 1.00–5.00 | $150.00 – $1000.00 | fine imperial | 2026-10-26 |
Retail market survey, per carat unless noted. Ranges describe what commercial to fine stones trade at; exceptional stones and provenance premiums sit above them.
Colourless Topaz
| Colour | water-clear colourless |
| Transparency | transparent |
| Clarity type | Type I - usually eye-clean |
| Phenomena | None |
| Appearance | Bright, colourless and highly lustrous; large clean crystals make impressive calibrated stones |
| Trade names | The feedstock for all irradiated blue topaz |
| Misnomers | 'Slave's diamond' - archaic diamond misnomer for colourless topaz • 'killiecrankie diamond' (Tasmania) |
| Typical sizes | Large stones plentiful; 5 to 25 ct common, museum giants known |
| Cutting styles | Faceted brilliants and step cuts; also carving of large crystals |
| Key separations | Vs diamond: singly refractive, hardness 10, thermal probe • Vs colourless zircon: zircon RI above limit, strong doubling, SG about 4.65 • Vs CZ, glass, YAG, GGG: singly refractive or different SG and RI • Topaz shows DR 0.008-0.010 on the refractometer with SG 3.53 |
| Sources (localities) | Brazil (main) • Sri Lanka • Nigeria • Russia • China • USA |
| Availability | Plentiful |
| Market notes | Sold modestly as a natural colourless gem but its real commercial role is as irradiation feedstock for blue topaz |
| Care notes | Cleavage risk in setting; no ultrasonic or steam |
| In short | Colourless topaz is abundant, bright and clean - the raw material from which nearly all blue topaz is made. On its own it is an honest, inexpensive diamond alternative that doubles slightly under magnification. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 1.00–15.00 | $3.00 – $20.00 | commercial | 2026-10-26 |
Retail market survey, per carat unless noted. Ranges describe what commercial to fine stones trade at; exceptional stones and provenance premiums sit above them.
Dark "Smoky" Topaz
| Colour | deep brown to smoky brownish orange, sometimes nearly opaque in tone |
| Transparency | transparent |
| Clarity type | Type I - usually eye-clean |
| Phenomena | None |
| Appearance | Rich coffee to smoky brown with warm orange flashes in fine material from Russia and Brazil |
| Trade names | Sherry topaz (brownish yellow to orange-brown) • burnt topaz for heated stones |
| Misnomers | 'Smoky topaz' is nearly always smoky QUARTZ, not topaz - the commonest topaz mislabel in the market |
| Typical sizes | 1 to 10 ct typical; large stones available |
| Cutting styles | Faceted ovals and cushions; Portuguese brilliant cuts for depth |
| Key separations | Vs smoky quartz: quartz RI 1.544-1.553, SG 2.65, vitreous but lower brilliance • Vs brown zircon: RI above limit, strong doubling, SG about 4.6 • Vs brown tourmaline: RI 1.62-1.64, stronger pleochroism, SG 3.05 • Some brown topaz fades slowly in daylight - warn clients |
| Sources (localities) | Russia (Urals) • Brazil • Ukraine (Volyn) • Mexico • USA (Utah) |
| Availability | Limited but steady |
| Market notes | Much 'smoky topaz' on sale is smoky quartz; the correct commercial conversation is to relabel and reprice honestly |
| Care notes | Perfect cleavage - no ultrasonic or steam; tepid soapy water; possible slow fading in light for some deposits |
| In short | Dark brown topaz is a natural colour-centre stone from Russia, Brazil and Ukraine, warm and affordable in larger sizes. Beware the trade's favourite mislabel: most 'smoky topaz' is actually smoky quartz. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 1.00–10.00 | $5.00 – $40.00 | commercial | 2026-10-26 |
Retail market survey, per carat unless noted. Ranges describe what commercial to fine stones trade at; exceptional stones and provenance premiums sit above them.
Sources
GIA gem encyclopedia · mindat.org · Wikipedia
Data compiled and fact-checked against gemmological literature, October 2026 (JDMIS gem reference). Properties are ranges accepted in gemmological practice; individual stones vary.
See also
Gemstone reference entries: gem #12 · gem #47 · gem #113 · gem #167 · gem #204
Related materials: Corundum · Diamond · Opal · Quartz · Spinel · Tourmaline
Identification wizard · All 83 materials · Singapore gem labs