Alexandrite tends to contain few inclusions. Good color change and strong colors have a higher value. Green/purple hues are more desirable than yellow/brown. Look for a medium lightness that allow for maximum color vibrancy. Stones that are too light look washed out while stones that are too dark can appear black. When certain types of long, thin inclusions are oriented parallel to each other, they can create an additional phenomenon called chatoyancy, or the cat’s-eye effect, increasing the alexandrite’s value.
Alexandrite’s pleochroism makes it a challenge for cutters. When fashioning alexandrite, cutters orient the gem to show the strongest color change through the crown. It’s crucial to position the rough so the fashioned stone shows both purplish red and green pleochroic colors face-up. Alexandrites are most commonly fashioned into what are called mixed cuts, which have brilliant-cut crowns and step-cut pavilions. Brilliant cuts have kite-shaped and triangular facets, while step cuts have concentric rows of parallel facets.
Again, good quality Alexandrite is expensive and rare. If you think you might have Alexandrite but aren’t certain, bring it in and let Goldwiser tell you for sure!
How to Clean and Care for Alexandrite
Alexandrite is relatively hard—8.5 on the Mohs scale. It has excellent toughness and no cleavage, which is a tendency to break when struck. This makes it a good choice for rings and other mountings subject to daily wear. Alexandrite is stable under normal wearing conditions, which means it’s resistant to the effects of heat, light, and common chemicals. Warm, soapy water is always safe for cleaning alexandrite. Ultrasonic and steam cleaners are usually safe unless the gem is fracture-filled.