Scientifically speaking, moonstone is the adularescent variety of orthoclase feldspar, but that definition falls short in describing this enchanting stone. When looking at a moonstone that glows like a bright full moon, it's easy to understand how the iridescent stones got their name. In his records of natural history, Pliny the Elder wrote about "star stones" he called "astrions," which are believed to be what we now know as star moonstones, or moonstones that display asterism. Pliny described an astrion as a stone that "imprisons a bright star, and although...it is like rock crystal, [it] has a brilliant blue sheen" and "radiating from the centre shines a star with the full brilliancy of the moon."
|Moonstone is best cleaned with warm soapy water and a soft brush or cloth. Excessive heat and sudden temperature changes can cause moonstone to crack, so steam cleaners should be avoided. Ultrasonic cleaners are also not considered safe for moonstones. Moonstones have cleavage in two directions, so they should be mounted in settings that can protect them from hard knocks.|
|It's hard to describe the colors of moonstone without using the word "magical." While a moonstone's bodycolor is basically colorless--white, clear, gray, or sometimes very pale yellow--the iridescent blue and bluish-green shimmer (adularescence) that glides across its surface makes "colorless" seem like a misnomer. Moonstones can also be brownish or green. |
|Ideal moonstones are colorless, eye clean or nearly so, nearly transparent (glassy) or at least semi-transparent, with a bright blue adularescence known in the trade as "blue sheen." In addition to the body color and sheen color, the orientation of the sheen is also important. Ideally the sheen is centered on the top of the stone and visible from every side. Moonstone cabochons over 9x7mm are also quite a bit more valuable than smaller stones.|
Name Origin and Meaning
When looking at a moonstone, it's easy to understand how the shimmering stones got their name. Their almost iridescent whiteness seems to glow like a full bright moon on an icy winter's evening. Moonstone was once known as "adularia," a name taken from the town of Mt. Adularia, in the Adula Mountains of Switzerland, one of the first moonstone sources. This is also the origin of the word "adularescence," the shimmering play of light that moves across the surface of a moonstone when it is turned.
Particularly popular in Art Nouveau jewelry around the turn of the 20th century, moonstone was a favorite of French goldsmith Rene Lalique, who featured moonstones in many of his nature-inspired works. Around that same time, for Christmas of 1906, Ernst Ludwig, Grand Duke of Hesse, gave his wife Princess Eleonore a magnificent Russian tiara featuring garlands of moonstones and turquoise curled around a diamond base. She no doubt enjoyed it for many years until November 1937, when many members of the royal family died in an airplane crash. The tiara was aboard that flight, but because it was in a strongbox, it survived the crash and is housed in London's Victoria and Albert Museum.
While moonstone is now regaining popularity in jewelry, it has been used in other decorative ways for thousands of years. In modern-day Sri Lanka, important buildings often have large half-moon-shaped steps, historically referred to as "a moon stone." This is a throwback to the ancient Sri Lankan tradition of tiling steps with moonstone mosaics at Buddhist temples, such as the Moonstone Temple in Anuradhapura. Built in 100 B.C., only the temple ruins remain, the moonstones long since stolen. Moonstones are considered sacred in India and are, therefore, displayed only on yellow cloth because yellow is considered to be a holy color.
When cut en cabochon, moonstones can also display asterism (a star) or chatoyancy (the cat's-eye effect).
Tiny inclusions known as "tension cracks" that are characteristic of moonstones are called "centipedes" because they look like tiny centipedes with multiple legs.
Along with pearl, moonstone is a birthstone for June.