Key properties
| Chemical formula | Mg3Al2(SiO4)3 |
| Crystal system | Cubic |
| Mohs hardness | 7-7.5 |
| Toughness | Fair to good |
| Refractive index | 1.714-1.742 |
| Optic character | SR (singly refractive; isotropic) - anomalous double refraction common |
| Dispersion | 0.0220 |
| Specific gravity | 3.62-3.87 |
| Cleavage | None; indistinct parting possible |
| Fracture | Conchoidal to uneven |
| Habit | Dodecahedral and trapezohedral crystals; most gem pyrope occurs as small rounded grains in alluvial deposits or peridotite xenoliths |
| Lustre | Vitreous, sometimes greasy; polish: Vitreous |
| UV fluorescence | Inert; chromium-rich stones may show faint red in long-wave UV |
| Pleochroism | None (isotropic); apparent colour shift possible from strong strain |
| Cause of colour | Iron (in solid solution towards almandine) with chromium contributing to fine reds ('chrome pyrope') |
| Typical inclusions | Rutile needle inclusions • irregular rounded included crystals of low relief • chrome-rich stones from diamond pipes can contain diamonds, enstatite and olivine |
| Stability | Stable to light and chemicals; slightly attacked by hydrofluoric acid |
| Heat sensitivity | Fuses readily under a jeweller's torch; abrupt temperature change risks fracture |
| Care and cleaning | Ultrasonic usually safe • steamer risky, best avoided • warm soapy water safe |
| Birthstones | January (garnet) • Aquarius • 2nd wedding anniversary |
| Availability | Limited as clean larger stones; most pyrope is small melee - Bohemian and Arizona material rarely exceeds 2 ct |
| Recognition | The archetypal 'garnet red' of Victorian and antique jewellery, though few know it by species name |
Varieties
Pyrope
| Colour | medium to dark red through slightly purplish red, sometimes blood-red; colourless is extremely rare |
| Transparency | transparent |
| Clarity type | Type II - typically included, but small stones usually eye-clean |
| Phenomena | Rare colour change (greenish in daylight to reddish purple in incandescent) in pyrope-spessartine mixes |
| Appearance | Warm blood-red to slightly purplish red, usually in small high-domed or faceted melee; the antique rose-cut pyropes are dense, glowing and dark. |
| Trade names | chrome pyrope (chromium-rich vivid red) • Bohemian garnet (historic Czech material; GIA discourages the name) |
| Misnomers | Cape ruby • Arizona ruby • Colorado ruby • Rocky Mountain ruby • Elie ruby (Fife, Scotland) • Bohemian carbuncle |
| Typical sizes | Seldom over 2 ct; most production is melee |
| Cutting styles | Faceted melee and small calibrated stones; antique jewellery used rose cuts and small cabochons |
| Key separations | vs ruby: ruby DR, RI 1.762-1.777, red fluorescence, pleochroism; pyrope SR, RI ~1.74, inert • vs almandine: almandine higher RI (~1.79) and SG (4.05), almandine spectrum shows 504/520/573 nm bands vs pyrope broad 564 nm band • vs red spinel: spinel RI 1.718-1.733, SG ~3.60, distinctive octahedra • vs synthetic red spinel: synthetic shows curved striae, flux clouds and different RI • vs garnet-and-glass doublet: magnification for join, RI on pavilion |
| Sources (localities) | Czech Republic (Bohemia) • South Africa (kimberlite-related) • USA (Arizona 'ant-hill' garnets, Navajo country) • Australia • Tanzania (colour-change) • Madagascar |
| Availability | Limited - antique markets carry plenty; new clean material is scarce |
| Market notes | Bohemian garnet jewellery is a collector category of its own. Arizona 'ant-hill' pyrope is collected by hand at very small sizes. Colour-change pyrope-spessartine (Tanzania) sells at a premium as a curiosity. |
| Care notes | Remove before any torch work - pyrope fuses easily |
| In short | Pyrope is the small, blood-red 'Bohemian garnet' of antique jewellery. Modern sources include Arizona and South Africa, and chromium-rich stones give genuinely vivid red, but sizes stay small. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 0.10–1.00 | $3.00 – $40.00 | melee to good commercial | 2026-10-26 |
| 1.00–3.00 | $20.00 – $100.00 | commercial to fine chrome pyrope | 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 #5
Related materials: Almandine Garnet · Andradite Garnet · Grossular Garnet · Hydrogrossular Garnet · Rhodolite Garnet · Spessartine Garnet · Tsavorite Garnet
Identification wizard · All 83 materials · Singapore gem labs