Alexandrite

Description

Alexandrite is an unusual stone. It is what is called a phenomenal stone. It changes colour depending on the lighting. In daylight it is a green colour similar to green tourmaline. In incandescent lighting, it turns to a rich red to a purplish red colour.

Lore and Uses

Alexandrite is named after Czar Alexander II as it was discovered in 1818 on the day of his birth in the Ural mountains near Ekaterinburg. The miners had been looking for emeralds, and findings these unusual stones, and examining them in daylight, they concluded that they had found emeralds. In the evening, while examining them by the light of the candles, they were astonished to find that the 'emeralds' were now green. In 1839 the mineralogist Baron Nils Adolf Erik Nordenskjšld identified them as a new gemnstone and gave it the name Alexandrite. Those original deposits have since been mined out, but new finds in Brazil and Africa have renewed the supply of these very beautiful stones. Madagascar is the source of the some of the finest of these new finds.

Alexandrites are among the most coveted of the coloured gemstones, with very fine specimens surpassing even diamonds in value. The most important factor in evaluating an Alexandrite is the quality of it's colour change. The finest quality will have a complete colour change, with both the red and the green colours being attractive, and relatively pure. In lesser specimens, the green can have a purple undertone, and the red will be a purplish-red with a bluey-green undertone. The clarity of the stone, and the quality of the cut take a back seat to colour. The largest known faceted Alexandrite is a 66ct specimen featured at the Smithsonian Institution in Washington, D.C. The largest known rough crystal specimen was a 1,876ct monster found in Sri Lanka.

The rarest form of Alexandrite is the Cat's Eye Alexandrite. This cabochon cut version of this already rare stone features a band of reflected light across the stone that appears to hover just above the stone, mimicking the effect of light on the eye of a cat.

Cautions

Alexandrite is a relatively hard stone, therefore it is suitable for virtually all types of jewellery. It can be susceptible to fracturing if it hit the wrong way, and at high heats it can change colour, but these are things that goldsmiths need to worry about. Typically if you damage the stone while wearing it as a ring, you're probably more concerned about your finger. No particular care must be taken with Alexandrite beyond having us check the setting on a regular basis.

There are quite a few Alexandrite substitutes in circulation. Since the late 1800's a synthetic corundum treated with vanadium has been on the market that has a similar, but not quite right, colour change. These are quite often larger stones, and typically have been passed down in the family, as 'Granny's Alexandrite'. In 1973 however, methods for growing a true synthetic Alexandrite that has the same chemical composition as the natural was developed. There are characteristic inclusions to this synthetic that we (or any other qualified gemmologist) can detect.

There are also colour change garnets, a very recent find, from Madagascar that have a very similar look, but again, any qualified gemmologist should be able to identify them.