What are moonstones and where do they come from?

This enchanting gemstone belongs to the large mineral group of the feldspars, of which almost two thirds of all the rocks on Earth consist. The moonstone is actually the feldspar variety known as 'adularia', a potassium aluminosilicate of gemstone quality, which is also found in the European Alps near the Adula Group – hence the name 'adularia'. Another synonym for moonstone is 'selenite', from the Greek 'selene' ('moon'). In their uncut state moonstones are rather unprepossessing and afford little idea of what it is that actually constitutes their charm: that mysterious shimmer of light. For that shimmer is not really shown to advantage until the art of the cutter has been brought to bear. Classical moonstones are always cut as cabochons, the most important thing being the correct height of the stone. The cutter must also align the axes of the crystal precisely into the zenith of the stone, for that is the only way in which he will bring about the desired light effect.Traditionally, the classical moonstones, almost transparent and with their bluish shimmer, come from Sri Lanka. However, they are also found in the USA, Brazil, Australia, Myanmar and Madagascar. Since bluish moonstones of good quality have been becoming more and more of a rarity in recent years, prices have risen sharply. For a few years, there have also been some green, brown and orange specimens on the market, as well as some with a smoky colour and some the colour of champagne, and some black and some reddish ones, mainly originating from India. Some have a cat's eye effect or a four-spoked star as well as the typical undulating shimmer of light. These stones are not only cut as cabochons, but also as artistic cameos or engraved with the faces of children, the moon or grotesques. But they too have the shimmer of light typical of the moonstone, as do the beads which are cut from suitable raw material for gemstone necklaces.