This transparent quartz has colors of both amethyst and citrine, and is called ametrine or amethyst-citrine.
Transparent, bicolored quartz with the colors of both amethyst and citrine in the same gem is called ametrine or amethyst-citrine. The contrasting colors give it an intriguing appearance.
Fine ametrine shows medium dark to moderately strong orange, and vivid to strong purple or violetish purple. Larger gems, usually those over 5 carats, tend to show the most intensely saturated hues. Dealers look for an attractive half-and-half distribution of each color, with a sharp boundary between the two colors at the center of the fashioned gemstone.
Ametrine is often cut as a rectangular step cut because that style nicely displays the bicolor effect. Cutters try to emphasize both colors equally.
Cutters sometimes fashion ametrines as mixed cuts or brilliant cuts and use internal reflections to mingle the amethyst and citrine colors. Ametrine is also popular in free-form or fantasy cuts.
There’s only one commercial source of natural ametrine: a deposit in eastern Bolivia, close to the Brazilian border. Legend has it that a Spanish conquistador discovered the location in the 1600s, but it was lost for more than three centuries. Ametrine began appearing on the market again during the 1970s. The mine, the Anahi, also produces natural amethyst and citrine.
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
WHY WE LOVE THIS GEMSTONE
No two ametrines look the same because the colors in each gem combine in a unique way.
There’s only one commercial source of ametrine, so the supply is very limited.
A CUTTER’S INSPIRATION
Cutters delight in finding ways to maximize the beauty of ametrine.