Buying certified diamonds at auctions means it is quite likely almost all the diamonds will be in setting and mostly will be antique diamond jewelery.
This is fall well and good and much antique jewelery can fetch a tidy sum.
However there are some points about buying certified diamonds at auctions to be aware off.
The cuts of early diamonds, by today’s standards, were not so good or precise and sometimes you can get a stone that does not have the sparkle or brilliance that a well cut stone of today will have.
Old stones tend to be worth more mounted than loose as the entire antiqueness of the piece is worth more than the diamond itself.
Old diamonds were cut by hand and not by machinery, so the precision is not there. This means there is a wider variation in the cuts and therefore a wider variation in the price. One needs to take great care when picking antique diamond jewelry. A large poorly cut antique diamond of the same weight of a modern well cut diamond can be worth up to 50 percent less so it is important to understand something about diamond cuts and the proportions that give the best sparkle and brilliance.
For example, the girdle (that outer rim of a diamond), tends to be cut thinner on antique diamonds which makes them more fragile and easily chipped. Modern diamond cuts will have a thicker girdle although too thick and it adds too much weight to the diamond reducing its sparkle and giving a poorer light refraction.
Modern certified diamonds can be bought at auction and these will tend to be lose stones and should always be accompanied by a certificate. The stones and certificate should always be inspected prior to the auction taking place.
If you are going to an auction at, say Sotheby’s, then you can be sure that any diamonds on offer there will be of excellent quality and will usually fetch a substantial price.
Buying certified diamonds at online auctions is potentially dangerous as you have no way of comparing the stones with the certificates. Only if there is a very clear cut returns policy whereby you do not lose any money is it worth considering the idea of purchasing a stone by online auction, certified or not.
If you can attend certified diamonds auctions in person, this is always the way to go to ensure you can see and possibly bid on a certified diamond.