Moonstones are a very simple gemstone to look at. Examined with a critical eye, they are almost colourless, translucent to transparent stones, nothing special, but then you notice the opalescent sheen and they are beautiful.
Moonstones belong to the Feldspar family, along with amazonites, labradorites and sunstones. They have an opalescent or adularescent sheen which can be a blue or white. You may see stones called rainbow moonstone but they are more properly colourless labradorites. The stone is mined in India, Sri Lanka, Myanmar, Tanzania, Kenya, Norway, New Zealand and Australia.
Historically, they are linked to worship of the moon and some Victorian jewellery contains moonstones carved with the face of the man in the moon. The stones are usually cut as cabochons, with the domed top.
Moonstones with a bluish sheen are the most sought after. They are usually not subject to much treatment although they can be coated to achieve the blue tint and there have been white synthetic spinels produced. Large moonstones with a blue sheen are getting very hard to find.
Moonstones are used in brooches, tie pins, rings, earrings and necklaces. They have a hardness of of 6 to 6.5 in Mohs’ scale of hardness so can show some scratches and wear.