A:Hi,
Interestingly enough the diamond that tre1129 mentioned was the highest price paid for a diamond but it wasn't the highest price paid per carat. The highest price paid per carat was actually paid by George Marciano at the purchase you mentioned. The price was 191,980$.
Another thing to think about is that the if sold, the Hope diamond would probably brake the record with its 42.5 carat.
Take care.
