What is the "magic number?"

Typically, every diamond buyer wants a stone size that hits the "magic number" (a half carat, 1 carat, 1.5 carats, etc.). Naturally, a large premium is charged once you reach these benchmark sizes, and the price-per-carat begins to jump geometrically instead of linearly.

To save money, consumers can try to find diamonds that weigh just below these sizes, since an untrained eye can't detect size differences in a well-cut diamond when they're within 8 points. Diamonds that weigh just below these benchmark sizes, however, are usually the result of a bad cut that unintentionally failed to hit the benchmark size.

Finding a diamond that weighs just short of the "magic number" and is still cut well, therefore, usually represents a great deal.