A rare and highly collectable variety of chrysoberyl, alexandrite ranks alongside ruby and padparadsha as the world's most desirable and expensive colored gemstones. Discovered in 1830 on the silver birch clad banks of Russia's Tokovaya River, this extraordinary gem was named after the young Czarevitch, Alexander Nicolajevitch who would later become Czar. For over 100 years now, alexandrite has commanded the higher positions in the pecking order of gemstone desirability.

Scant availability combined with remarkable color change, excellent durability and a sparkling adamantine luster, alexandrite is an excellent gem for the connoisseur. However, while ranked as one of the world's most desirable and expensive gem types, it must be born in mind that not all alexandrites are of a comparable quality. Understanding exactly where value lies in this extraordinary gem type is essential to be able to make accurate quality appraisals, or make safe and rewarding purchases.

The Three Colors Of Alexandrite?

Like most other gemstones, the quality of color in alexandrite is the all-important factor. However, with alexandrite there is arguably three color factors that need to be considered within a single jewel: the daylight color, the incandescent-light color, and the degree of change between them.

Top quality alexandrite exhibits an attractive metallic bluish green color under daylight. Free from being too light, too dark, brownish or gray, the green color witnessed should be attractive within its own right.

Exactly the same principle of "attractive within its own right" should also be applied to the reddish color seen under incandescent-light. It too, should be free from being too dark, brownish or gray.

On top of these two color considerations is the degree of change experienced between the two colors – the greater the change, the more desirable the alexandrite. However, all three factors should be accounted for as a balanced sum of three parts. A striking green alexandrite that shows a vivid color change, is let down if the incandescent-light color is too dark or brown.

Carat Weight & The Pricing Of Alexandrites

As a rare gem in under supply and over demand, alexandrite can be expensive. Fine quality specimens under two carats are obtainable but costly. Large alexandrites that go above the five or six carat mark are considered extremely collectable and possess high ticket prices as the world's wealthiest collectors vie for highly desirable but scarce specimens.

Freedom From Inclusions & The Pricing Of Alexandrites

As a gem that is noted to suffer from smallish crystal sizes and tendencies for poor freedom from inclusions, parallels can be drawn to ruby – prices rise stratospherically as clean alexandrites go above the three carat mark. Unlike its non-color changing brother chrysoberyl, alexandrite has been placed in the Type II category of colored gems, meaning that inclusions are typical.

Shape & Cut

Faceted alexandrites are found in wide variety of shapes and styles. However, due to the high expense of rough alexandrite, the shape of "native cut" polished gems are often tightly bound to that of the rough gem. As a consequence, alexandrites are regularly submitted for recutting, which pushes per carat prices up even further as the strive for perfection dictates a second visit to the polishing wheel and the inevitable weight loss it entails.

While oval and cushion cuts are the most frequently seen alexandrite cuts, other shapes such as emerald and heart cuts are also relatively common. Large round cut alexandrites are seldom seen as high rates of weight loss during cutting push already expensive per carat prices up even further. Cabochons are most regularly seen in cat's eyes and star alexandrites.

Cat's Eye & Star Alexandrites

Cat's eyes and stars in all gem varieties have long been coveted for their beautiful and mysterious optical effects. Glance at a cat's eye alexandrite and you will see a band of light silently gliding across the surface. Sometimes a fainter second arm of light will intersect the bright band, creating a color changing star alexandrite.

Sources Of Alexandrite

Perceived as the finest locale for alexandrite, Russian origin specimens possess a historical pedigree that means some people are prepared to pay a premium for them over alexandrites of other origins. In reality, alexandrites every bit as fine have been unearthed in Burma, Brazil, Sri Lanka, India, Madagascar, Tanzania and even Zimbabwe.
 

Today, Tanzania and Madagascar are responsible for a large proportion of the alexandrite on the market. Both locales can produce exceptionally fine specimens such as this huge 17.90 mm x 11.83 mm certified 15.58 Carat Tunduru alexandrite featured left. Also, increasingly found on the market in the last few years are fine quality specimens from Andrapradesh, India.

As a rare gemstone, alexandrite is a highly desirable product that is sold at a premium. While the desirable features of an alexandrite are the three color factors, just like other gemstones, attributes such as carat weight, clarity, cut and origin also need to be considered.

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