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Alexandrite

Alexandrite is the colour-change variety of chrysoberyl, a beryllium aluminium oxide coloured by chromium, that appears green to bluish green in daylight and red to purplish red under incandescent light. The strength and cleanness of that change, more than any other quality, decides whether a stone is fine or merely interesting, and clean stones with a strong change are rare at any size. Byrex Gems offers natural alexandrite to the jewellery trade from Toronto, filmed unedited, with prices for approved buyers and viewings by appointment.

Where to buy alexandrite in Toronto

Byrex Gems lists 9 alexandrite online today. 7 of them come with a report from laboratories including GIA, Gübelin and GRS. Origins include India and Brazil. Viewings are at our Toronto office, 27 Queen Street East, Suite 407, steps from Queen subway station, by appointment. We have supplied coloured gemstones and natural fancy colour diamonds to jewellers and designers since 1988, and welcome private clients by appointment. Prices are shown to approved trade accounts; private clients can ask us on WhatsApp, where we reply within 12 hours, or by email within 24 hours. Every stone ships insured, worldwide.

Among the alexandrite listed today: 11.40 ct Oval Alexandrite, Gübelin, India Unheated, 7.93 ct Radiant Emerald Cut Alexandrite, GRS, Unheated, 5.11 ct Oval Alexandrite, GIA, Unheated, 1.74 ct Oval Alexandrite, GIA, Unheated, 1.28 ct Oval Alexandrite, GIA, 1.23 ct Oval Alexandrite, GIA, Unheated, 1.75 ct Round Alexandrite, Gübelin, Brazil Unheated, 1.44 ct Square Cushion Alexandrite, 0.65 ct Square Cushion Alexandrite.

What is alexandrite and why does it change colour?

Alexandrite is chrysoberyl, BeAl2O4, in which a small amount of chromium replaces aluminium in the crystal. Chromium absorbs light in the yellow part of the spectrum and leaves two windows of transmission, one in the green and one in the red. Daylight is rich in green and blue, so the green window dominates and the stone looks green or bluish green. Incandescent light is rich in red, so the red window dominates and the same stone looks red, purplish red or raspberry. Chrysoberyl is 8.5 on the Mohs scale, tougher than most coloured stones and without troublesome cleavage, so alexandrite is well suited to rings.

The original source is the emerald mines of the Ural Mountains in Russia, where the stone was found in the 1830s. Brazil's Hematita deposit in Minas Gerais, discovered in 1987, produced the finest modern material, with a clean change from bluish green to purplish red. Sri Lanka yields larger but often less saturated stones with a more olive to brownish red change. India, chiefly Andhra Pradesh and Odisha, Tanzania, Madagascar, Zimbabwe and Myanmar also produce alexandrite.

How laboratories describe the colour change

A report identifies the stone as natural alexandrite, which in laboratory usage means chrysoberyl with a distinct colour change; chrysoberyl with a weak or absent change is described as chrysoberyl, sometimes with a note of slight change. GIA, Gübelin, SSEF, GRS, Lotus and AGL describe the two colours observed, typically in daylight-equivalent and incandescent light, in their own wording.

Many reports and most dealers also describe the degree of change, and this is where buyers must read carefully. Some laboratories and most of the trade express it as a percentage, from a weak change through moderate to a strong or complete change, with figures such as eighty or one hundred percent meaning that most or all of the stone shifts colour. The percentage is an observer's estimate of how much of the stone's face changes and how fully, not an instrument reading, and the same stone can be described differently by different observers.

Origin opinions are offered for alexandrite by several laboratories on the basis of inclusions and trace-element chemistry, stated as a country: Brazil, Sri Lanka, India, Russia, Tanzania. Reports sometimes record origin as inconclusive. Treatment is not routine for alexandrite and reports normally state that no indications of treatment were found.

What to check before buying an alexandrite

Check the change yourself, under a daylight-equivalent lamp and then under an incandescent bulb, with the stone viewed from the top. Look for a green or bluish green that is clearly green, not olive or brownish, and a red or purplish red that is clearly red, not brown or muddy. The best stones change cleanly across the whole face; weaker stones change only partly, or show both colours at once in daylight, which reads as a greyish mix.

Many alexandrites are included. Fine needles, fingerprints and small crystals are common, and a lightly included stone with a strong change is a better purchase than a clean stone with a weak one.

Sizes above one or two carats with a strong change are scarce, and above five carats they are rare in any origin. Pairs are difficult, since two stones seldom change to the same degree; Byrex describes two stones as a pair only when the parcel paper or report says so, and otherwise as a close match. Cat's eye alexandrite, cut as a cabochon to show a sharp band of light from parallel needle inclusions, is judged on the sharpness of the eye and the strength of the change together.

What drives the value of an alexandrite

The colour change is the first driver of value, and both halves count. The market pays most for a stone that is a saturated green or bluish green in daylight and a saturated red or purplish red under incandescent light, with the change complete across the face. A strong green that turns only brownish, or a fine red that comes from an olive daylight colour, is worth considerably less.

Clarity comes next. Because fine alexandrite is often included, a clean stone with a strong change commands a sharp premium, while a stone with eye-visible inclusions is discounted but still saleable if the change is excellent. Size multiplies value steeply above one carat and again above three, since clean, strongly changing rough is rare from every source.

Origin opinions add a premium in a familiar order: Russian stones for their history and rarity, then Brazilian for the quality of the change, then Sri Lankan and Indian material, which is often larger but less saturated. Cat's eye alexandrite is valued on the sharpness and centring of the eye as well as the change. Synthetic alexandrite, colour-change synthetic corundum and colour-change garnet are look-alikes with separate, much lower markets, and a report from a recognised laboratory is the safeguard.

History of alexandrite and its look-alikes

Alexandrite was found in the emerald mines of the Ural Mountains near Yekaterinburg in the 1830s and was named for the future Tsar Alexander II of Russia. Its colours matched the red and green of the Imperial military, and it became a stone of the Russian court. The Ural deposits produced the stones that defined the species, with a clean green-to-red change, but they were largely worked out by the early twentieth century, and Russian alexandrite in fine quality is now found chiefly in old jewellery and collections.

The twentieth century brought Sri Lankan material in larger sizes and the first synthetics. Flux-grown and pulled synthetic alexandrite appeared in the 1970s and is still produced. The 1987 discovery at Hematita in Minas Gerais, Brazil, renewed the supply of top-quality natural stones, although the deposit was worked out within a few years and fine Hematita stones are now traded mainly on the secondary market.

Today alexandrite comes from Brazil, Sri Lanka, India, Tanzania, Madagascar and Zimbabwe in modest quantities, and the finest stones appear at auction with laboratory reports describing the change and the origin.

Buying alexandrite from Byrex Gems

Since 1988, Byrex Gems has supplied alexandrites to the jewellery trade from Toronto. The confidence of more than seven thousand trade customers has been earned one stone at a time. Many of our alexandrites come with reports from GRS, SSEF, Gübelin, GIA and other leading laboratories, and each stone is filmed in our office, exactly as it is.

Approved trade buyers see prices online. Everyone else is welcome to write: WhatsApp +1 (437) 450-3786 brings a reply within hours, and an email to info@byrex.com an answer the same day, seven days a week. What is listed is a part of what we hold: more alexandrites are kept in the vault, and what we do not hold ourselves we can source through our offices worldwide. We receive clients by appointment in Toronto, Hong Kong, Bangkok and Dubai.

Alexandrite: questions buyers ask

How strong should the colour change be in a good alexandrite?

Strong enough to be obvious: a clear green or bluish green under daylight-equivalent light and a clear red or purplish red under incandescent light, across the whole face. Dealers and some laboratories describe the degree as a percentage; it is an observer's estimate, not a measurement.

Is alexandrite treated or heated in any way?

No. There is no routine treatment for alexandrite, and reports normally state that no indications of treatment were found. The colour change is a natural property of the chromium in the chrysoberyl. Synthetic alexandrite exists and is identified by inclusions and spectra.

How can I tell natural alexandrite from synthetic?

Only a laboratory can say with confidence. Flux-grown and pulled synthetics have been made since the 1970s, and colour-change synthetic corundum and spinel are common imitations. Laboratories separate them by inclusions and spectroscopy, and Byrex supplies stones with reports from GIA, Gübelin, SSEF, GRS, Lotus or AGL.

Does the report state where an alexandrite comes from?

Several laboratories offer an origin opinion for alexandrite, stated as a country such as Brazil, Sri Lanka, India or Russia, based on inclusions and trace-element chemistry. It is an opinion, and some reports record origin as inconclusive.

What is cat's eye alexandrite?

Alexandrite with parallel needle inclusions cut as a cabochon so that a sharp band of light moves across the dome. It is judged on the sharpness and centring of the eye together with the strength of the colour change. Fine examples are rare.

Is alexandrite hard enough for daily wear?

Yes. Chrysoberyl is 8.5 on the Mohs scale, harder than every gem except diamond and corundum, and it has no troublesome cleavage. It suits rings and bracelets, and ordinary cleaning methods, including ultrasonic, are safe for stones without large fractures.

Does Byrex source alexandrite for private clients?

Byrex sells to the jewellery trade and receives private clients by appointment in Toronto. Stones not in the collection, including Brazilian or Russian alexandrite with specific reports, are sourced on request through Byrex's offices and partners. Prices are shown to approved trade buyers.

Can I see the colour change in person in Toronto?

Yes, by appointment at 27 Queen Street East, Suite 407, Toronto. Byrex shows each alexandrite under a daylight-equivalent lamp and an incandescent bulb, side by side, with the laboratory report on the table.

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