Loose diamonds carat oval really describes a loose oval diamond of whatever carat. Probably the best sizes to buy in diamonds is either just slightly below a half carat or a carat or a 1.5 carat. The difference in size is negligible and one can still, for a .9 carat diamond, say it is about a carat. The big difference is in the cost.
A .9 carat, or just a fraction under, is going to be considerably cheaper than a full one carat or slightly over diamond.
Fred Cuellar, in his book, “How to Buy a Diamond” coined the term, ‘buying shy’. Here he talks about buying just under the carat or half a carat weight.
The price of a diamond jumps dramatically when it reaches the full or half carat.
A good idea is to look at the size. The diameter of a one carat diamond is about 6.5 millimeters. A .90 carat diamond is 6.3 millimeters. The difference is only the thickness of a piece of paper or a human hair. If you put a one carat and a .90 carat diamond side by side you would be extremely unlikely to be able to tell the difference. Yet the difference could represent anywhere from 300 to 3000 dollars! Depending on the size of the stone.
Taking an SI1-I Stone.
.50ct would be around $1,590
.49ct would be around $1,300 saving almost 200 dollars
1.00ct would be about $6,380
.90ct would be about $5,140 saving almost 1,240 dollars
1.50ct would be about $12,170
1.49ct would be about $9,510 saving around 2,660 dollars
2.00ct would be about $18,620 saving a massive 3,220 dollars
1.90ct would be about $15,400
So for the sake of a hairs thickness a considerable saving can be made.
Of course diamond cutters are aware of this and it is therefore difficult to get a slightly lower carat size as a result. Many diamond cutters will work to get the diamond up to scratch, as it were, to gain the full size so sometimes it may be better to accept a slightly bigger gap between a smaller stone and the full weight.
Of course there is the issue of the stone, in the eyes of the receiver if you are giving it as an engagement ring for example, being too small and not up to par. You can always say it is about a carat, (most people do not ask for an exact size anyway)
So loose diamonds carat oval can be a good buy if one decides to ‘buy shy’ and get what is really an equally fine diamond very slightly smaller but with a bigger saving in cost!