Whether projecting from pegmatite walls or encrusting cavities in volcanic rock, quartz abounds worldwide. People have used quartz in jewelry for thousands of years. When quartz displays the colors of amethyst and citrine in a single gem, the material is called ametrine or amethyst-citrine. Ametrine’s only commercial source is the Anahi mine in Bolivia.
No place else
There is only one commercial source for ametrine: the Anahi mine in Bolivia.
Nature’s gift
The presence of amethyst and citrine colors in a quartz crystal is a rare gift of nature.
Cutter’s choice
Ametrine’s colors blend, combine, and contrast uniquely in each gem.
Facts
- Mineral: Quartz
- Chemical composition: SiO2
- Color: Bicolor orange/yellow and purple
- Refractive index: 1.544 to 1.553
- Specific gravity: 2.66 (+0.03/-0.02)
- Mohs hardness: 7
Ametrine, also known as trystine or by its trade name as bolivianite, is a naturally occurring variety of quartz. It is a mixture of amethyst and citrine with zones of purple and yellow or orange.
The colour of the zones visible within ametrine are due to differing oxidation states of iron within the crystal. The citrine segments have oxidized iron while the amethyst segments are unoxidized. The different oxidation states occur due to there being a temperature gradient across the crystal during its formation. Artificial ametrine is grown with the hydrothermal method using solutions doped with specific elements, followed by irradiation of the created crystals.
Ametrine in the low price segment may stem from synthetic material. Green-yellow or golden-blue ametrine does not exist naturally.