There are many sites that sell loose diamonds for cheap prices. You don’t need to everything about diamonds in order to sort through which are the best but some basic facts are essential.
Firstly you really should have in mind exactly the sort of diamond you want and including the color, clarity, cut and weight. You should also have in mind what you want the diamond for, a ring or a pendant or even a broach perhaps.
Then you go and do a search for that particular diamond.
There is no shortage of diamonds. There is only an apparent shortage to keep the prices up. However many of the dealers or jewelers online do not keep stocks of all the diamonds they advertise but simply keep a few samples. This keeps their costs down and enables them to sell at a cheaper price. They generally source the diamonds ordered from wholesale diamond dealers when an order is placed with them by a customer.
So it is relatively easy to get the diamond you want and, if money is no object, then of course it is a piece of cake. However money is usually an object and you obviously do not want to pay more for your diamond than you have to.
When you check out some websites check that the dealer has a fixed address posted on the site. If there is no fixed address posted on the site it is probably better to seek one or those that do. The same with a phone number where you can actually talk to a person. Many dealers and jewelers now have web sites so you can easily find them.
Also they should be a member of the better Business Bureau and the Diamond Dealers Association of the country in which they operate.
A good quality diamond dealer will have a clear returns policy. This should enable you to return the diamond if you find it is not what you expect when you get it home in natural light. In addition you can have a diamond graded to see if it matches what you ordered. If not and you return it you should be able to get your money back from the dealer.
A diamond should come with a graded report from an established gemological laboratory such as the GIA for example.
It is certainly possible to buy loose diamonds for cheap prices provided one has some patience and a clear cut idea of what you want and just uses a bit of common sense.