|
Red zircon
At one time this variety was known as hyacinth,
although w did not match the description of hyacinth left
us by Plir . the Elder. Indeed, a number of orange-red or
brownish rc stones were called by this name until the knowledge
- mineralogy, which began to be acquired in the eighteen,
century, caused these names based purely on color to r abandoned.
Appearance Red-often brick or orange red,
but sontimes even a violet red. Like all zircons, it has considerat
luster, shown to advantage by the zircon cut (a modifr, form
of brilliant cut) sometimes used for these stonRound or oval,
mixed cuts with a brilliant-cut crown a, step-cut pavilion
are, however, more common, as they = with most other colored
stones.
Distinctive features As always with zircons,
the mark birefringence is a useful means of recognition. The
color (with faint pleochroism) and luster can make red zirc
look like some spinels and possibly garnets, but the gems
are singly refractive. Marked birefringence also ea: ily distinguishes
it from corundum, in which the effect much weaker. It has
the physical properties of high zircc with refractive indices
above the range of normal refre tometers. As with other zircons,
however, it almost alwa, has a highly distinctive absorption
spectrum.
Occurrence Red or reddish zircon comes mainly
frc Sri Lanka, Cambodia, and Thailand.
Value It is more or less equal in cost to
the best blue zi cons, and is therefore not one of the highest
priced se ondary gems.
Simulants and synthetics These zircons are
not suft ciently well known to be imitated. Red zircon is
not pr( duced synthetically.
|
