Most of the diamond sold today come from Africa, but Australia and Russia are suppliers of uncut diamonds as well.
The first step in manufacturing Tiffany Style Diamonds is to give them to a cleaver or sawyer. They both, essentially, perform the same task: That is to cut--or cleave--the GIA Certified Diamonds in two pieces in order to bring out the best profile that will determine the end product of the stones.
In order to cut diamond necklace at the best angles to produce the most fire, much of the original GIA Certified Diamonds rough is lost, resulting in a great decrease in the diamonds carat weight.