Tuesday, June 1, 2010

June Birthstones - Moonstone, Pearl & Alexandrite

June Birthstones - Moonstone, Pearl & Alexandrite

The traditional birthstone for June is Alexandrite. Alexandrite is a variety of chrysoberyl and displays a color change (alexandrite effect) dependent upon the nature of ambient lighting. Alexandrite results from small scale replacement of aluminium by chromium ions in the crystal structure, which causes intense absorption of light over a narrow range of wavelengths in the yellow region of the spectrum. Alexandrite from the Ural Mountains in Russia is green by daylight and red by incandescent light. Other varieties of alexandrite may be yellowish or pink in daylight and a columbine or raspberry red by incandescent light. The optimum or "ideal" color change would be fine emerald green to fine purplish red, but this is exceedingly rare. Because of their rarity and the color change capability, "ideal" alexandrite gems are some of the most expensive in the world.

The modern birthstones for June are the Moonstone and Pearl. Moonstone has a 6.0 hardness on the Mohs scale. Its name is derived from a visual effect, or sheen, caused by light reflecting internally in the moonstone from layer inclusion of different feldspars. Moonstone is feldspar with a pearly and opalescent luster.

Pearls have been highly valued since antiquity. Just like the shell of a mollusk, a pearl is made up of calcium carbonate in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes of pearls (baroque pearls) occur. The value of the pearls in jewelry is determined by a combination of the luster, color, size, lack of surface flaw and symmetry that are appropriate for the type of pearl under consideration. Among those attributes, luster is the most important determination of pearl quality according to jewelers. All factors being equal, however, the larger the pearl the more valuable it is. Large, perfectly round pearls are rare and highly valued. Teardrop-shaped pearls are often used in pendants.

See more Moonstone, Pearl & Alexandrite here.

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