Amethyst
Amethyst is the purple variety of quartz and the most valued member of the quartz family. Its colour ranges from pale lilac to deep violet, sometimes with flashes of red or blue, and is caused by small amounts of iron within the crystal that have been altered by natural radiation in the surrounding rock. The finest stones are a deep, even purple and are transparent.
Amethyst forms as crystals lining cavities in volcanic rock, and large geodes from Brazil and Uruguay are familiar decorative pieces. Today the main sources are Brazil, Uruguay and Zambia, with Zambian material often noted for its deep colour.
The name comes from the Greek "amethystos", meaning "not intoxicated", reflecting the ancient belief that the stone protected its owner from drunkenness. Until the 18th century amethyst was counted among the cardinal (most precious) gems alongside diamond, ruby, sapphire and emerald; it became much more affordable after large deposits were found in Brazil. It has long been associated with royalty and the church, and amethyst is traditionally set in bishops' rings.
Heating amethyst changes its colour to yellow or orange, and much of the citrine on the market is heat-treated amethyst. Partial heating can produce ametrine, which shows both purple and yellow zones. Amethyst can fade if left in strong sunlight for long periods. Synthetic amethyst is grown in laboratories and has the same properties as the natural stone, so it can only be reliably identified by a gemmological laboratory.
Amethyst at a glance
| Colour | Pale lilac to deep violet, purple, red-violet |
|---|---|
| Hardness (Mohs scale) | 7 |
| Composition | Silicon dioxide |
| Crystal structure | Trigonal; hexagonal prisms |
| Lustre | Vitreous |
| Transparency | Transparent to translucent |
| Where it is found | Brazil, Uruguay, Zambia, Madagascar, India, Sri Lanka, Namibia, Russia, Mexico, Canada and USA |
| Birthstone | February (modern, trad) |
| Wedding anniversary | 4,6 |
Caring for amethyst
Amethyst is hard (7 on the Mohs scale) and durable, but it can be chipped by a hard knock. Clean it with warm soapy water and a soft brush or cloth. Ultrasonic cleaning is usually safe for untreated stones, but avoid steam cleaning and sudden changes in temperature. Keep amethyst out of strong sunlight and away from heat for long periods, as this can fade the colour. Store separately from harder stones to avoid scratches.
In folklore
The beliefs below are traditional folklore, included for interest. They are not scientifically proven, and nothing here is medical advice.
In ancient Greece and Rome, wine was drunk from goblets carved from amethyst in the belief that the stone would prevent intoxication. Medieval soldiers wore amethyst amulets to keep a cool head in battle, and it was believed to guard against evil thoughts and bring good judgement. Amethyst is a symbol of sobriety, peace and piety, and is associated with St Valentine, who is said to have worn an amethyst ring. It is the zodiac stone of Pisces and Aquarius.
Amethyst is traditionally considered a calming, protective and spiritual stone. Crystal healing lore holds that it relieves stress and anxiety, encourages restful sleep and peaceful dreams, and aids meditation and intuition. It is also said to help with breaking bad habits and addictions, in keeping with its ancient association with sobriety. It is linked to the crown and third eye chakras.
Related stones
Citrine, ametrine, prasiolite (green quartz), rock crystal, rose quartz, smoky quartz, chalcedony and agate. Stones of similar colour include purple fluorite, iolite, purple sapphire, tanzanite, lepidolite and charoite. Fluorite is much softer and spinel and sapphire much harder, which helps tell them apart.
For the technically minded
| Scientific name | SiO2 |
|---|---|
| Density | 2.65 |
| Refractive index | 1.544 – 1.553 |
| Double refraction | 0.009 |
| Cleavage | None |
| Streak | White |
| Fluorescence | None to very weak |