Blue zircon is one of the traditional modern birthstones for December.
Zircon is a tremendously important mineral, indeed its prominence led to the emergence of the discipline of 'zirconology' in gemology.
It is the uranium and thorium that cause such tremendous variations in the physical properties of zircon.
Zircon is typically classified as low, medium and high zircon, in reference to the presence of optical properties.
Zircon was the first crystal to form in molten granite as it cooled to form rock.
The most popular zircon today is blue zircon, usually occurring with green pleochroism, which can result in interesting teal-like colors.The high birefringence of zircon makes it necessary for the cutter to orient the table of the stone to the optic axis; otherwise the interior may look fuzzy, due to facet image doubling. Colored stones are most often brilliant or emerald step cut.Round stones are often given a 'zircon cut', which is similar to a standard round brilliant cut, but with an extra row of facets at the edges. Some brown varieties, mostly found in Southeast Asia, may be heated to produce colorless and blue zircon.Low zircon has higher traces of radioactive uranium and thorium, which causes an alteration in physical structure, rendering it near-amorphous, though its physical appearance remains the same as high or medium zircon.Low zircon is typically green to brownish in color.