The five best test that to know for diamonds are:
1. The stone is known for its clarity. When light falls on it it gives out the spectrum of seven colour.
2. It is the hardest stone and therefore does not burn except when intensely heated.
3. Diamond can never be cut into a smooth round stone. It's cutting has to be prismatic.
4. When compared to any other stones in carats it is heavier.
5. Hence it has an optimum weight that can be embedded in a particular jewellery.