Why does a diamond sparkle so much?

The sparkling isn't just the high refractive index - the shape matters too. Diamonds are cut so that a light ray falling on the diamond is reflected multiple times inside the diamond and therefore sends light out in all directions. Actually, diamonds don't shine, they reflect.Nov 3, 2012 read more

Diamonds are cut for maximumx sparkle with consideration being given to flaws within the diamond. These flaws in the diamond could affect its sparkle in the following way. The reflection and refraction of the light and the way it plays inside the gem is responsible for the sparkle, so the sparkle of a diamond depends entirely upon the light and the path it takes in to and out of the diamond. read more