 Moonstone
the birthstone for June, 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 hues.
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.
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