Quartz
Amethyst
The most prized variety of quartz.
- Mohs hardness
- 7
- Crystal system
- Hexagonal
- Composition
- SiO₂ with Fe (irradiated)
- Colours
- Pale lilac, Deep purple, Reddish purple ('Siberian')
- Origins
- Brazil, Uruguay, Zambia
- Birthstone
- February
Amethyst is iron-bearing quartz coloured by natural irradiation. Once as valuable as ruby and emerald, the discovery of vast Brazilian deposits in the 19th century democratised it - but fine deep purple from Uruguay still commands strong prices.
The ancient Greeks believed amethyst prevented intoxication; the name derives from amethystos - 'not drunken'.
Worn by Catholic bishops and ancient Greek symposiasts alike for sobriety and clarity of thought.
Treatments
What to know
- Heat treatment - converts amethyst to citrine or 'green amethyst' (prasiolite)
- Irradiation - restores or deepens colour
Care & handling
How to wear it
- Generally safe for ultrasonic; avoid prolonged heat which can fade colour
- Protect from prolonged sunlight
Jewellery use
Setting the gemstone
Excellent everyday gemstone. Suitable for all jewellery types.
Famous examples
- · Morris Amethyst Brooch
- · Delhi Sapphire (mislabelled amethyst)
Same family