almost seems magical with a ghostly shimmering glow floating
in a crystalline material. The Romans thought that moonstone
was formed out of moonlight. Moonstone is a variety of feldspar
and the shimmer, which is called schiller or adularescence,
is caused by the intergrowth of two different types of feldspar,
with different refractive indexes.
In Europe, moonstone is considered the birthstone for June,
although in the United States it shares that distinction with
alexandrite and pearl.
Moonstones come in a variety of colors. The body color can range
from colorless to gray, brown, yellow, green, or pink. The clarity
ranges from transparent to translucent. The best moonstone has
a blue sheen, perfect clarity, and a colorless body color.
Sometimes moonstone will have an eye as well as a sheen. Another
related feldspar variety is known as rainbow moonstone. In this
variety of labradorite feldspar, the sheen is a variety of rainbow
Fine moonstone is quite rare and becoming rarer. It is mined
in Sri Lanka and Southen India. The rainbow variety can also
be found in Madagascar.
Moonstones are usually cut in a smooth-domed cabochon shape
to maximize the effect. Sometimes they are carved to show a
man-in-the-moon face. Moonstone beads also display the sheen
very well and are simply stunning against a black dress.