Green in sunlight. Red in lamplight. Colour-changing alexandrite is nature’s magic trick.

Alexandrite, a rare variety of the mineral chrysoberyl, is renowned for its remarkable colour-changing ability. It can appear green under daylight or fluorescent lighting, but shifts to a reddish-brown or purplish-red hue when viewed under incandescent light, such as from a lamp or candle. This striking transformation occurs due to the mineral’s unique light absorption properties.

Often referred to as “emerald by day, ruby by night,” alexandrite's colour change is so dramatic that it is commonly known as “the alexandrite effect.” While other gemstones can also change colour with different light sources, the effect of alexandrite is particularly vivid.

Additionally, alexandrite is a strongly pleochroic gem, displaying different colours—typically green, orange, and purple-red—when viewed from various angles. However, the stunning colour shift is primarily due to its special light-absorbing qualities, not its pleochroism.

Given its rarity, especially in larger sizes, alexandrite is one of the more expensive chrysoberyl’s. It is also one of the birthstones for June, alongside cultured pearl and moonstone.

Information on this page has been sourced from the Gemmological Institute Of America (GIA) to learn more about Alexandrite’s please visit https://www.gia.edu/alexandrite to learn more or click the above learn more button.