Sugilite

Sugilite is a rare silicate mineral containing potassium, sodium and lithium. The vivid purple jewellery-grade material is an aggregate of tiny grains that contains about 1–3% manganese oxide, and in commercial quantities it comes only from the Wessels mine in South Africa. At the place in Japan that gave the mineral its name it forms small brownish-yellow grains that are not used in jewellery.

Sugilite is mainly an ornamental and jewellery stone: cabochons, beads, pendants, small carvings and ring stones are made from it. In cutting, carving and polishing it behaves like jade; it does not break or crack easily, which makes it useful in jewellery. Quality grades are set by colour (tone and saturation), texture, hardness and translucency.

It has a hardness of 5.5–6.5 on the Mohs scale. It can scratch glass; a steel knife scratches it only with difficulty. Its specific gravity is 2.74–2.8 g/cm³.

Its best-known localities: Iwagi Islet, Ehime Prefecture, Japan; Wessels mine, Hotazel, Northern Cape, South Africa; Mont Saint-Hilaire, Quebec, Canada; Liguria (Cerchiara mine, near Faggiona), Italy; Woods mine, near Tamworth, New South Wales, Australia.

Its colour is purple or bluish purple, looking more reddish in incandescent (yellowish) light. It ranges from opaque to translucent, with a glassy or resinous lustre. The texture can be even, or mottled, veined or banded; under a microscope tiny interlocking grains can be seen. Its hardness is 5.5–6.5. Being an aggregate of tiny grains, it is durable in jewellery: it does not crack easily and resists heat and light. Sugilite mixed with chalcedony: some material from the Wessels mine contains an important amount of chalcedony; its colour is paler and it is slightly harder (6–6.5).

On the “street to diamond” value ladder it sits on step 6 of nine: Fine ornamental and collector stone. What matters most in sugilite is the saturation and evenness of the purple, the evenness of the texture (mottled, veined or banded pieces are less sought after), crack-free and large pieces, and translucency. Because purple sugilite in commercial quantities comes only from the Wessels mine, supply is limited; in 1987 GIA unofficially estimated the total amount in the mine at 12 to 15 tons. No colour-enhancing treatment is known to be applied.

Today crystal-therapy practitioners claim that sugilite is linked with the third eye and crown chakras, helps meditation, “absorbs negative energy”, supports people through difficult periods, brings sleep without nightmares, and strengthens confidence and imagination. The same circles claim that sugilite relieves headaches, toothache and back pain, strengthens immunity and the heart, regulates blood circulation and “purifies” the body fluids, and helps scars heal. There is no scientific evidence that sugilite relieves pain, strengthens immunity or the heart, heals scars, “absorbs energy” or improves sleep; for pain, sleeplessness or heart complaints, see a doctor rather than relying on a stone. The stone's purple comes from about 1–3% manganese oxide in its structure. This section reports beliefs; it is not health information. There is no scientific evidence for these claims and no stone replaces medical treatment.