Of all the birthstones, June’s birthstone is perhaps the rarest of all. To many, alexandrite is an enigma; a gem they have heard of, but never seen. A gemstone chameleon, alexandrite has been described as “emerald by day; ruby by night”.

Alexandrite is a unique and rare colour-changing variety of the mineral chrysoberyl, and was first discovered in the 1830’s in Russia’s Ural Mountains. Named after Alexander II, this gem captured the imagination of Russia with its vivid red and green colours mirroring the national military colours. These early deposits of alexandrite were of exceptional quality but were quickly depleted.

More recent deposits have been discovered in Sri Lanka, East Africa and Brazil, but overall the quality of these crystals is a far cry from the original Russian alexandrite gems.

Alexandrite

An example of a top quality alexandrite, with intense colours and clean clarity.
Image via GIA & Evan Caplan Fine Gemstones.

Due to the complex way that alexandrite absorbs light and the incorporation of chromium in the crystal lattice, alexandrite crystals will appear as either green or red, depending on the light source. In daylight, or fluorescent light, it is a gorgeous greenish-blue colour. When viewed in incandescent light however, the stone reflects a purplish-red (sometimes brown) colour. This is one of the key identifying properties of alexandrite.

Alexandrite has a hardness of 8.5 (out of 10) on Moh’s hardness scale, making it harder than a more common colour-changing gem, garnet. Gem-quality alexandrite is exceptionally rare and top quality pieces will be sold for thousands of dollars per carat, making it one of the more expensive coloured gemstones. Most available alexandrite weighs less than 0.25cts in the rare case of finding gems larger than 1ct, expect to pay tens of thousands of dollars per carat.

Virtually all original Russian alexandrite is now in the hands of private collectors or housed in museums.

British museum alexandrite

A 43ct alexandrite gem on display in the British Museum.

 

Imitation Alexandrite

Like many gemstones, synthetic and imitation alexandrites can easily be found in the market place. Often, people have inherited “alexandrite” from their mother, or grandmother and contact us wanting to know what the family jewels are worth. In the case of one such client, we asked her to send us a picture of her “alexandrite” in natural daylight, and she sent us the picture below.

Picture sent us from a client who believed she’d inherited an alexandrite from her mother. Her mother had purchased the ring on an overseas trip, believing it to be the real thing.

It was immediately clear to us, based on the daylight colour of the stone, that what she had was not alexandrite at all. Alexandrite is blue-green in daylight, and the vivid pink colour displayed by her stone indicated straight away that her gem wasn’t alexandrite. Instead, it was a more common synthetic and imitation alexandrite, made of corundum. Synthetic corundum (or synthetic sapphire) is coloured with vanadium oxide, giving the appearance of alexandrite.

Synthetic colour-changing corundum was first grown in 1909, and today, many “heirloom” jewellery pieces contain this synthetic corundum. Many examples of these “gems” have been sold to tourists in Alexandria, Egypt and Mexico (contrary to the name similarity, alexandrite is not mined, nor does it occur in Alexandria) after the Second World War. They still exist in private collections where, sadly, the owners are under the misconception that they own one of the rarest coloured gems ever.

Synthetic alexandrite is widely grown nowadays using flux growth and the Czochralski method. Despite being used widely for jewellery, synthetic alexandrite is used predominantly as a laser

Luckily, for those celebrating their birthday in June, alternative birthstones exist in the form of cultured pearls and moonstone. Both birthstones are easily available and much more budget-friendly than Alexandrite. Contact us and let you know which of the June birthstones you are looking for.