Key properties
| Chemical formula | KNa2(Fe,Mn,Al)2Li3Si12O30 |
| Crystal system | Hexagonal |
| Mohs hardness | 5.5-6.5 |
| Toughness | Good |
| Refractive index | 1.607-1.610 |
| Birefringence | 0.0010-0.0030 |
| Optic character | Uniaxial negative; gem material reads as aggregate (-) |
| Specific gravity | 2.69-2.80 |
| Cleavage | Poor — rarely observed in massive gem material |
| Fracture | Granular to uneven |
| Habit | Massive interlocking aggregates; euhedral prismatic crystals very rare |
| Lustre | Vitreous; polish: Waxy to vitreous |
| UV fluorescence | Inert |
| Pleochroism | None apparent in massive material |
| Cause of colour | Manganese (Mn3+), with iron contributing to the reddish cast in some material |
| Typical inclusions | Mottled mineral mix — gem 'sugilite' is usually sugilite with quartz/microcrystalline silica and manganese minerals; quartz areas give spot readings near 1.54 |
| Stability | Stable to light and to normal heat; attacked by hydrofluoric acid |
| Heat sensitivity | Low under normal bench conditions |
| Care and cleaning | Warm soapy water safe; ultrasonic and steam risky because of the granular structure |
| Availability | Limited — one main source (Wessels mine, South Africa) worked sporadically since 1979; parcels reach the market irregularly |
| Recognition | Niche — strong following among designers and collectors of 'new age' purple stones |
Varieties
Sugilite
| Colour | deep reddish-purple to bluish-purple; best grades translucent 'gel' purple, lowest grades mottled grey-purple |
| Transparency | opaque |
| Clarity type | Opaque to semi-translucent — graded by colour saturation and translucency ('gel' grade at top) |
| Phenomena | None |
| Appearance | Rich imperial-purple to magenta, often subtly mottled; the best looks like solidified grape jelly with a waxy glow |
| Trade names | Royal Azel • Royal Lavulite • lavulite |
| Misnomers | None established; dyed magnesite/howlite and purple stevensite are sold fraudulently as sugilite |
| Typical sizes | Mostly small to medium cabochons; large clean pieces rare and priced accordingly |
| Cutting styles | Cabochons • beads • inlay; translucent gel material occasionally faceted |
| Key separations | RI about 1.61, SG about 2.74, distinctive 550 nm band with 411/419/437/445 nm lines. vs charoite: charoite RI about 1.55, SG 2.5-2.7, fibrous swirled lilac with white streaks. vs purple chalcedony: RI 1.53-1.54. vs dyed magnesite: dye in cracks, SG about 3.0, too uniform |
| Sources (localities) | South Africa (Wessels mine and N'Chwaning, Kalahari manganese field, Hotazel, Northern Cape) • Japan (Iwagi, Ehime — type locality, brownish) • Canada (Mont Saint-Hilaire, Quebec) |
| Availability | Limited — supply depends on occasional Wessels batches |
| Market notes | Prices step sharply with saturation and translucency; untreated deep-purple Wessels material is the value benchmark |
| Care notes | Wears reasonably well in pendants and beads; avoid HF-bearing chemicals and hard knocks on granular material |
| In short | South Africa's purple manganese-field treasure: opaque to gel-translucent magenta, single-source, and separated from look-alikes by its 1.61 RI, 2.74 SG and 550 nm band. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 1.00–10.00 | $10.00 – $60.00 | opaque to mottled cabochons | 2026-10-26 |
| 3.00–15.00 | $100.00 – $400.00 | fine translucent gel purple | 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 #26
Related materials: Corundum · Diamond · Opal · Quartz · Spinel · Topaz
Identification wizard · All 83 materials · Singapore gem labs