Thursday, October 14, 2010

What is Pleochroism and Chatoyancy?

Pleochroism and chatoyancy are two ways that light is refracted or reflected in gemstones, (and some wood).

Pleochroism is an optical phenomenon in mineral grains of rock that appear to be different colors when viewed at different angles.
This is caused by a double refraction of light.
Some gemstones that are pleochromic are Adalucite,Iolite,Tanzanite,and Zoisite.

Chatoyancy is the optical reflection seen in some gemstones. Caused by the fiberous inclusions or cavities in the rock. they are always perpendicular to the direction of the fiber.
Chatoyant stones are Tiger Eye, some Quartz,(Iris rare!) Chryoberyl, Beryl (Aquamarine, Tourmaline and Moonstone).


  1. This I'm afraid is far too technical for me to follow!!! :)

  2. If I said it's from the way the light shines through the rocks would have been better? =)

    double refractives are two wave lengths of light, color depends on what wave you see.

    optical refracton refers to the change of direction of light and speed it changes that direction.


  3. I found some chatoyant (cats eye looking) bi-colored (pink to green) tourmaline cabs, really cool looking! Waiting for the right customer/piece to put them in. :)

  4. I can't wait to see them in that right piece!