Gemstones - Alexandrite

Alexandrite is named after the Russian tsar Alexander II (1818-1881), with the very first crystals being discovered in April 1834 in the emerald mines near the Tokovaya River in the Urals. Alexandrite is a young gemstone, but has a noble history. Because Alexandrite shows both red and green, the colors of old Imperial Russia, it became the national stone.

Tiffany & Co. master gemologist George Frederick Kunz was also fascinated with Alexandrite, and created some beautiful rings and platinum ensembles at the end of the 19th and beginning of the 20th century. Smaller Alexandrites were occasionally also used in Victorian jewelry from England.

What give Alexandrite it's draw and lust is its ability to change its color from green in daylight to a shade of red in incandescent light. This unique characteristic makes it one of the most valuable gemstones of all.

Alexandrite is very scarce gemstone mainly because of its chemical composition. It is basically a chrysoberyl, but differs from other chrysoberyls because they only contain iron, titanium and chromium. It's the chromium which accounts for the fascinating color change and rarely vanadium may also play a part, but in small circumstances.

Like other gemstones, Alexandrite were born millions of years ago in a metamorphic environment, but its formation required very specific geological conditions. The chemical elements beryllium (chrysoberyl) and chromium (the color changing agent) have contrasting chemical characteristics and do not occur together because of contrasting rock types.

Russia has remained the primary source of all Alexandrites since gems from the mines of the Urals became available. When the Alexandrite deposits were thought to have been exhausted in Russia, this situation changed dramatically in 1987, when Alexandrites were discovered in Brazil.

Brazilian Alexandrites show both a distinctive color change, good clarity and color. The color of the Brazilian Alexandrites is admittedly not as strong a green as that of Russian Alexandrite, but the color change is clearly visible. Today Brazil is one of the most important deposits of Alexandrite in economic terms.

Alexandrites are also obtained from mines in Sri Lanka, but the hue of these stones compares less than favourably with that of the Russian Alexandrites. They appear green in daylight and a brownish red in incandescent light. In southern Tanzania has also produced some outstanding Alexandrites since the mid-1990s as well as India, Burma, Madagascar and Zimbabwe.

Alexandrite's hardness is 8.5 on the Mohs scale.

The more distinct the color change, the more valuable the Alexandrite becomes. A fine Alexandrite should show a vivid bluish-green in daylight and a purplish-red in incandescent light. A fine Alexandrite should not have any trace of brown or grey too. If the origin of the Alexandrite is known to be Russia (proof needs to be in hand) then the value increases to an unimaginable price. A faceted Alexandrite above 1ct will be the most expensive gemstone in the world, rarer than fine ruby, sapphire or emerald.