More about Hinduism and diamonds
Diamonds are pretty much unbreakable, which is what makes them so useful. They are used on the tips of tools so that etchings can be made in rocks, or metal. But the main thing that people think of when they think of a Diamond are the facets. Diamond cutting is about getting all the right angles so that the light is most utilized and shines out in all directions as much as possible. This comes from Hindu tradition. You can see the same idea in a Rudraksha bead. A Rudraksha bead is meant to symbolize Shiva's Eyes, the word for Diamond in Sankrit is Vairja which is the same word for lightning bolt, and lightning is associated with the God Indra. The Vairja is important to both Hindu and Buddhist cultures.
http://en.wikipedia.org/wiki/Vajra
This is a Rudraksha Seed, you can see it has many faces just like a diamond.
Ancient Hindu scriptures mention eight types of diamonds
1. Hanspati: transparent white color like a conch,
2. Kamlapati: transparent pinkish white, like lotus petal.
3. Vajraneel: transparent blue-white, like the color of the neck of a blue jay,
4. Vanaspati: transparent green-white, like fresh blade of grass,
5. Shyamvajra: transparent smoky-grey color
6. Telia: oily,and dark color.
7. Sanloyi: yellow-green or pale green color,
This ritual object is known as a Vairja, and it is meant to represent lightning and diamonds.