Moonstone is one of the varieties of the feldspar group mineral known as orthoclase. During the formation, orthoclase and albite separate into different layers. When light falls between its thin layers, it is scattered producing a specific phenomenon known as adularescence - the light that appears to billow across a gem.
The moonstone gem is typically colorless however it can occur in a wide range of colors such as gray, mocha brown, yellow, orange, green, pink, blue and white. Moonstone is not known to be treated or enhanced in any way but there have been attempts for certain color enhancements.
As one of the most well-known gems in the orthoclase feldspar, moonstone is a potassium aluminum silicate which is transparent to opaque oligoclase. It is also known to exhibit a distinct sheen under certain lighting which renders it as one of the most remarkable gemstones available on the market.
This gem was extremely popular in the Art Nouveau era which took place more than 100 years ago. At that time, moonstone was used to decorate innumerable pieces of gemstone jewelry created by popular artists such as Rene Lalique and his contemporaries.
Also, moonstone is abundant and inexpensive. Greater transparency is more desirable and valuable.
The color of the stone is another price factor. Moonstones that have a bluish color are in high demand and more valuable. However, moonstone is an affordable gemstone that has been desirable since ancient times. Often used in cabochons, necklaces and pendants, some societies even sew it into garments as a charm.
Moonstone deposits are found as constituents in feldspar-rich granitic and syenitic pegmatites all over the world. It is primarily mined in India, Sri Lanka, Myanmar, Australia, Madagascar, Tanzania and Brazil.