The precise origin of wholesale diamonds is still not truly known. However, it is believed that the first loose diamond ever discovered in South Africa was done so by a fifteen year old boy by the name of Erasmus Jacobs. While searching for a stick to clear a drain one day, he picked up a stone sparkling in the sunlight and gave it to his sister. It was seen by a friend of the family and was ultimately discovered to be a 21.25 carat stone.
While the weight of a Tiffany Style Diamonds is important, it doesnt necessarily provide the "perceived size" of a loose diamond. A shallow cut diamond will have a greater diameter, and will therefore look larger.
Pink and blue ideal cut diamonds are especially popular and have been sold at higher dollars per carat than any other loose gemstones in history. Red, green, and purple loose diamond are among the rarest of the rare.