Reportedly discovered in Russia’s Ural Mountains on the day Crown Prince Alexander (later Czar Alexander II) came of age in 1830. The gem was named for the prince. It also displayed a remarkable phenomenon, appearing green in daylight, but red in candlelight – and those were the colors of the imperial family.
In finest quality, alexandrite is among the world’s rarest and costliest gems.
Birthstone for June and gem for the 55th wedding anniversary.
Phenomenon: Shows a distinct change of color in different types of light.
Color: Green to blueish green in daylight or fluorescent light. Red to purplish red in incandescent light. The colors tend to be muted, and never reach the intensities that emerald and ruby can. Fine alexandrite does a dramatic switch from bluish green to ‘raspberry’ red.
Clarity: Often lightly included. Minor clarity characteristics are accepted.
Cut: Usually faceted in traditional shapes and styles. Must be carefully oriented to show the color change most effectively when cut.
Carat Weight: Seldom over 5 carats, especially in fine quality.
Alexandrite is one of the gems for which there are no established treatments.
A variety of the mineral species chrysoberyl.
Composed primarily of beryllium, aluminum, and oxygen; chemical formula BeAl2O4. Color caused by trace amounts of chromium (which also colors emerald and ruby). The gem’s special chemistry causes it to change color according to the spectral content of the light in which it’s viewed.
Alexandrite is the best-known color-change gem, and the phenomenon is often called the alexandrite effect. Other gems that can exhibit a similar change include garnet, sapphire, spinel, and tourmaline.
Alexandrite generally has excellent wearability.
Hardness: High scratch resistance. Rates 8.5 on the Mohs Harness Scale
Toughness: Excellent resistance to chipping and breaking.
Stability: No characteristic concerns.
Cleaning: Liquid cleaner, or detergent and water. Ultrasonic is usually safe, unless noticeable clarity characteristics are present.