A to Z of Gemstones: A: Ametrine


Gemstone family: Quartz

Crystal System: Trigonal

Moh's scale of hardness: 7

Lustre: Vitreous

About: Ametrine is a mixture of Amethyst and Citrine with bands of purple and yellow-orange.  The colour of the zones visible within ametrine are due to differing oxidation states of iron within the crystal. The different oxidation states occur due to there being a temperature gradient across the crystal during its formation.

Origin: The main source of Ametrine is Bolivia.

Use in jewellery: Ametrines’s lustre and durable hardness make, it suitable for jewellery that has secure settings to protect the stone from wear.  Depending on the transparency of the stone which can be anything between transparent to opaque, amethysts are cut into faceted gems, cabochons or beads.

Treatments, synthetics and imitations:  Ametrine can also be created by heat treating amethyst.  Synthetic ametrine is also available.