Faceted sugilite, cut by Mark Oros of Hashnu Stones & Gems. Design: Sakura 96 (modified) by Marco Voltolini. 20.5 cts, 18 mm x 17 mm x 12 mm. © Hashnu Stones & Gems. Used with permission.
What is the color of sugilite? Grape jelly purple is a good description. More popular among consumers in Asia than North America, this is a very rare and beautiful opaque gem material with an unusual appearance.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
The most important factor in grading sugilite is color. The deepest color receives the highest grade. A mottled appearance under close inspection doesn’t affect the overall value, provided the overall color remains deep. However, lighter areas mixed with dark purple will lower the value.
Sugilite is available in fairly large sizes. Gems over ten carats are common and receive no additional value per carat.
Translucent sugilite isn’t yet available in sufficient quantities for market values to be established.
“Metal & stone (precious & semi-precious) 28,” silver, sugilite, and bronze. Photo by Eric Golub. Licensed under CC By 2.0.
| Data | Value |
|---|---|
| Name | Sugilite |
| Crystallography | Hexagonal; occurs as subhedral grains; massive. |
| Refractive Index | 1.590-1.610 |
| Colors | Light brownish yellow; lavender; intense reddish violet (manganiferous) purplish, dark rose-red. |
| Luster | Vitreous. |
| Hardness | 6-6.5 |
| Wearability | Very Good |
| Fracture | Conchoidal |
| Specific Gravity | 2.74 (variable) |
| Birefringence | 0.003-0.005 |
| Cleavage | Poor |
| Luminescence | None |
| Luminescence Present | No |
| Enhancements | Heating (rare). |
| Typical Treatments | Heat Treatment |
| Transparency | Opaque to translucent |
| Absorption Spectrum | Strong band at 4190, weak band at 4110; broad diffuse band centered at 5700. |
| Phenomena | Chatoyancy (rare) |
| Formula | (K,Na)(Na,Fe+3)2(Li2Fe+3)Si12O30+Mn |
| Pleochroism | Not reported. |
| Optics | o = 1.610; e = 1.607 (India: o = 1.595; e = 1.590: Africa: o = 1.610; e = 1.606). Uniaxial (-). |
| Optic Sign | Uniaxial - |
| Etymology | Named for its discoverer, Professor Ken-ichi Sugi, a Japanese petrologist. |
| Occurrence | Aegirine syenite, biotite granite, manganese deposits. |
Sugilite: Kuruman, South Africa (gem 3.66). Photo © Joel E. Arem, PhD, FGA. Used with permission.
Outside of Asia, sophisticated gem shoppers haven’t shown great interest in sugilites. Perhaps younger consumers in North America and other parts of the world will find this material’s bold, striking color more attractive. Of course, its rarity may appeal to collectors.
Discovered in 1944 on Iwagi Islet in southwestern Japan, the first known sugilites were actually tiny, yellow crystals. They had no gem value. In 1955, some dark pink prismatic crystals were found in central India. However, this material wasn’t cuttable.
In 1975, a core-drill sample from a manganese mine near Hotazel, South Africa revealed a thin seam of sugilite. This material had enough manganese content to give it a deep purple color. Small but significant, the deposit became the first source of gem-quality sugilite and launched the gem’s now famous association with purple. (Some specimens can approach an amethyst-like color).
Owl with snake, carving made from South African sugilite, 5.25″ x 5.50″ x 3.25”. © Arizonacrystalco. Used with permission.
In 1979, a massive deposit estimated at 10-20 tons was found near Hotazel. Unfortunately, it lies 3,200 feet underground. The combination of the technical challenge of mining the material and the limited demand for sugilite means much of it remains underground. Half of the deposit may have the opaque, grape jelly color of known gem-quality sugilites. However, a very small percentage, perhaps 0.1%, may be translucent. Known as “sugilite gel,” this material is extremely rare and highly prized.
Custom cast 14k gold diamond ring with sugilite gel inlay. Jewelry and photo by Jessa and Mark Anderson. Licensed under CC By 2.0.
A number of trade names for sugilite have emerged. Material more lavender than purple is sometimes called “Royal Lavulite.” Hotazel, South Africa has inspired names such as “Royal Azel” and “Royal Lazelle.” The Wessels Mine itself has also inspired the name “Wesselite.”
Sugilite, “Royal Azel.” Photo by TIS0421. Licensed under CC By-SA 3.0.
Variations of the name “Cybelene” are also given to sugilites, perhaps alluding to the myth of Cybele and Attis and its connection to the flower violet.
This South African specimen displays royal purple bands of parallel, fibrous, and very chatoyant sugilite, alternating with bands of lavender sugilite with an almost wrinkled foil appearance. It also contains thin bands of gray-black manganese shale. 11.2 x 10.9 x 4.7 cm, N’Chwaning III Mine, Kuruman, Kalahari MN Field, Northern Cape Province, South Africa. © Rob Lavinsky, www.iRocks.com. Used with permission.
Deep purple, grape jelly sugilites get their color from traces of manganese. They may resemble sogdianite gemstones. However, sogdianites contains traces of titanium and zirconium, which sugilites lack. A chemical analysis can distinguish the two species. Note that sogdianite is a much rarer mineral than sugilite and far less likely to be found either cut or carved.
Another rarely encountered gemstone, purpurite can show a purplish rose color similar to sugilite. However, purpurites have a higher specific gravity (SG) than sugilites.
This intarsia by Jim Kaufmann consists of bands of malachite, sugilite, opal, and fire agate. Photo © All That Glitters. Used with permission.
A wide variety of gemstones have been used to simulate or imitate the appearance of sugilites. Gem labs have reported instances of dyed marble, dyed quartzite, dyed magnesite, and dyed and heated beryl confused with or presented as natural sugilites.
Consumers can easily find so-called “synthetic sugilite” for sale online. However, this material is most likely an imitation, not a lab-created version of actual sugilite. In these cases, “synthetic” means “fake” in the popular sense. Buyer beware.
Sugilites generally receive no treatments or enhancements. However, heating may lighten some dark material.
Notable sources include the following:
Sugilite within a matrix of an unidentified, unstable brown mineral. Woods Mine, Tamworth, Darling Co., New South Wales, Australia. Photo by Matthew Goodwin. Licensed under CC By 3.0.
With poor cleavage, a hardness of 6-6.5, and a tough tenacity, sugilites can make durable gemstones. However, protective settings are advisable for preventing scratches, especially if this material is worn as a ring. Otherwise, these gems require no special care.
For cleaning recommendations, consult our gemstone jewelry care guide.
Sugilite ring with scrollwork. Jewelry and photo by Jessa and Mark Anderson. Licensed under CC By 2.0.
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