Stones That Change Colors in the Light

Alexandrite

• Alexandrite is an expensive gemstone which may change color from incandescent light to daylight. Alexandrite is a variety of chrysoberyl. Russian alexandrite, which is very rare, can change from red to green. Other forms of alexandrite changes from green to purple or bluish-purple. Alexandrite is able to change colors in an extreme way because when it is under incandescent light, it is able to transmit the warmer, red colors. When it is in daylight, there is less red and therefore does not transmit that color, appearing blue or even green.

Sapphires

• Like alexandrite, sapphires can change colors from daylight to incandescent light. In incandescent light, many blue sapphires appear dark, or almost black. Another type may appear blue in natural light and appear purple in incandescent light.

Garnets

• Color-change garnets change from brown to a rose shade when going from daylight to incandescent light. A blue garnet can change to a purple from daylight to incandescent light. Blue garnets are found in Kenya.

Other Stones

• Other stones that may change color from incandescent lighting to daylight include tourmaline, spinel, diaspore, iolite and beryl. But these changes are not as pronounced as the changes in alexandrite, sapphire or garnet.

Other Types of Color Change

• Pleochroism is a type of color change that occurs when a person looks down a different axis within the gemstone. Play of color is what you see when you look at an opal and see the rainbow of color. Iridescence causes the stone to show a rainbow of colors.