Moonstones are a gem subspecies of Feldspar, composed of Potassium Aluminum Silicate. Moonstone, and its siblings Blue/Black Spectrolite and Labradorite and Salmon coloured Peristerite all exhibit a phenomenon known as Adularescence, meaning that a streak of colours appear to move across the surface of the gem as it is rotated or rocked. Only the variety called Moonstone is transparent.
The finest stones, found at Mount Adularia in Switzerland and in Meetiyagoda in Sri Lanka, are completely clear and exhibit a Blue/White billowing cloud across the face of the stone. Fine, perfectly clear and flawless stones have not been found for a long time, as these mines cease producing a long time ago. They command a much higher price than you would expect from such a fragile stone.
All Feldspars cleave or split easily and are a difficult stone to set. They are also temperature sensitive, prone to thermal shocking and are scratched easily. Hardly the description of a valuable gem. Yet they endure as earrings, brooches and pendants and even in rings.
Today, lesser quality Moonstones are found throughout the southern hemisphere. While the stones found today cannot compare to the deposits of yesteryear, they are still quite nice but much less dramatic and therefore they are much less expensive.
There is a subspecies of moonstone called Rainbow Moonstone that exhibit other colours than Blues such as reds, greens and yellows, but they are in fact Bytownite. This is another cousin in the Feldspar family and it is unique in that it can sometimes display a star as well as a billowing cloud.
All of these wonderful gems are available in our shop, set and unset, for your viewing pleasure.