Alexandrite:

This is a color change stone and belongs to the chrysoberyl family of gems.

Alexandrite was discovered in 1830 on the birthday of Alexander II in the rural mountains in Russia, and named after him.

Can be cleaned in ultra-sonic cleaners (no longer than 3 to 5 minutes).
It is emerald green during daylight and a purplish red under artificial lights or twilight.

Chrysoberyl is known for its fine cat's eyes of greens and greenish yellows and grey.
Cat's eyes are very expensive and hard to find stones.

Alexandrite is well known as a extremely scarce and very costly gem. The quality of color change with different illumination is the primary basis for its quality and price. No more than one person out of 100,000 has ever seen a real one. 

Stones over 5 carats are almost unknown. Brazilian gems tend to have pale washed out colors when cut. Recently a find was made in Ceylon of a limited number of crystals, these tend to be olive green in daylight and a blue-red-black at night.

A few are found from time to time in Brazil, Ceylon, Russia, and Rhodesia.

One of the most fascinating gemstones throughout history is alexandrite: a gem variety of the mineral chrysoberyl that actually changes color from green in daylight to red in incandescent light. The first time you see it, it is hard to believe your eyes! Gems that show special optical effects are known as phenomenal stones. Chrysoberyl dominates this category, because not only is alexandrite the most spectacular color change gem, cat's eye chrysoberyl has the most dramatic eye. Alexandrite has a distinguished and glamorous past: it was discovered in 1830 in Czarist Russia. Since the old Russian imperial colors are red and green it was named after Czar Alexander II on the occasion of his coming of age.

Alexandrite can be found in jewels of the period as it was well loved by the Russian master jewelers. Master gemologist George Kunz of Tiffany was a fan of alexandrite and the company produced many rings featuring fine alexandrite in the late nineteenth and early twentieth century, including some set in platinum from the twenties. Some Victorian jewelry from England features sets of small alexandrites.

Alexandrite is also sometimes available as an unset stone but it is extremely rare in fine qualities. The original source in Russia's Ural Mountains has long since closed after producing for only a few decades and only a few stones can be found on the market today. Material with a certificate of Russian origin is still particularly valued by the trade. Some alexandrite is found in Sri Lanka and Zimbabwe and Brazil but very little shows a dramatic color change. For many years, alexandrite was almost impossible to find because there was so little available.

Then in 1987, a new find of alexandrite was made in Brazil at a locality called Hematita. The Hematita alexandrite shows a striking and attractive color change from raspberry red to bluish green. Although alexandrite remains extremely rare and expensive, the production of a limited amount of new material means a new generation of jewelers and collectors have been exposed to this beautiful gemstone, creating an upsurge in popularity and demand.

When evaluating alexandrite, pay the most attention to the color change: the more dramatic and complete the shift from red to green, without the bleeding through of brown from one color to the next, the more rare and valuable the stone. The other important value factors are the attractiveness of the two colors - the more intense the better - the clarity, and the cutting quality. Because of the rarity of this gemstone, large sizes command very high premiums.

Pearls: the Alternate to Alexandrite

Lustrous and versatile, pearls are the perfect gift alternative to Alexandrite. Whether they are saltwater or freshwater, natural or cultured, pearls can be found to match skin tones, blend with hair color, accent casual and formal wear. Select from round to unusual baroque shapes, in lusters from iridescent white to burnished black. Wear them as chokers or let them cascade from neck to waist.  Depending on your mood, wear them with jeans, pinstripes or a gown.  For more information on pearls, read our article on how to judge a pearl & our intriguing info about pearls.
See also: Proper Care.

Moonstone:

Moonstone almost seems magical with a ghostly shimmering glow floating in a crystalline material. The Romans thought that moonstone was formed out of moonlight. Moonstone is a variety of feldspar and the shimmer, which is called schiller or adularescence, is caused by the intergrowth of two different types of feldspar, with different refractive indexes.

In Europe, moonstone is considered the birthstone for June, although in the United States it shares that distinction with alexandrite and pearl.

Moonstones come in a variety of colors. The body color can range from colorless to gray, brown, yellow, green, or pink. The clarity ranges from transparent to translucent. The best moonstone has a blue sheen, perfect clarity, and a colorless body color.

Sometimes moonstone will have an eye as well as a sheen. Another related feldspar variety is known as rainbow moonstone. In this variety of labradorite feldspar, the sheen is a variety of rainbow hues.

Fine moonstone is quite rare and becoming rarer. It is mined in Sri Lanka and Southen India. The rainbow variety can also be found in Madagascar.

Moonstones are usually cut in a smooth-domed cabochon shape to maximize the effect. Sometimes they are carved to show a man-in-the-moon face. Moonstone beads also display the sheen very well and are simply stunning against a black dress.