One of the most prized gemstones in the world, Alexandrite, is known to display this feature. It can be a brilliant apple green in sunlight and will appear strawberry red under incandescent lighting. It has been said to be “Emerald by day, Ruby by night”. The reason for this change is the way the light stimulates the chromium atoms in the crystal structure and the way our eye perceives these changes. Due to this mysterious phenomenon and it’s incredible rarity, Alexandrite has been highly sought after since its discovery in the early 1800s. Another gem which displays a beautiful change of colour is the very rare colour change variety of garnet. The colour change can be intense and equal to the colour change of top quality alexandrite.
This feature should not be confused with play of colour where the gem’s colour will change as the gem is titled in the same light source. An example of play of colour is opal.