All, Roger Drey spoke the truth as any professional gemstone cutter
will tell you. I would like to add a little more about sapphires.
The reason you do not see many emerald cut, round cut, and marquis
cut sapphires in 1+ct sizes is because of the shape of the natural
rough and the cutting operations in Thailand. First of all most
sapphire rough comes out of the ground roughly in the shape of a
potato. This shape makes the ideal cut an oval or rectangular
cushion. Thai cutters cut for weight first and shape second.
Secondly all must understand that most of the worlds sapphires are
cut in Thailand. This occurs because the Thai Gem Traders buy most
of the rough in the world. They are the biggest gamblers and bet
their money on their skills in treatment and low cost of production
to make money. Therefore, sapphires are enhanced and cut for yield
first and foremost. Whenever I am out buying parcels of 1+ct
sapphires emerald cuts, marquis, and rounds always are priced at a
premium. A lot of times I will look for poorly cut ovals of good
clarity and color to recut. Over the years these parcels have become
more rare as Thai cutters have improved their cutting.