In well cut diamonds all the light that enters the top is reflected out. Labs have different criteria when looking at the cut.Gia is very strict. The cut is the human element in the diamond.To cut an excellent Gia requires a lot of skill. The cut affects the sparkle of the diamond.
Carat is a seed from a tree in Africa and each seed has a mass of 0.2 grams.These seeds were used to trade in Africa they were a currency. So a 1ct diamond has a mass of 0.2 grams.
Clarity is the internal perfection of the diamond.
Diamonds appear in all colours, each colour is assigned an alphabetical letter. Visibly white diamonds are from D-I in colour.D is the whitest.Diamonds from J-k show a slight yellow tinge. Generally engagement rings in white metals should use diamonds between D-I in colour and yellow gold diamond rings from J-k.