The crystal structure of zircon is tetragonal crystal system.
The natural color of zircon varies between colorless, yellow-golden, red, brown, blue, and green.
All of which leaves little time for social media: she posts on Instagram no more than a dozen times a year.
And so it was rather a surprise three weeks ago when Priscilla shared a paparazzi picture taken of her and the singer Tom Jones, 76.
Colorless specimens that show gem quality are a popular substitute for diamond and are also known as "Matura diamond".
The name derives from the Persian zargun meaning gold-hued. It occurs as a common accessory mineral in igneous rocks (as primary crystallization products), in metamorphic rocks and as detrital grains in sedimentary rocks.
Zircons contain trace amounts of uranium and thorium (from 10 ppm up to 1 wt%) and can be dated using several modern analytical techniques.