1.00 Carat Because it's the most popular weight, diamonds experience a price jump at 1.00 ct. The price jump is especially high for round diamonds, and, at this weight, you'll get the most savings by choosing a fancy shape. With a budget of $4,500, you can find a great one-carat diamond.

Market research shows that the average size of an engagement ring center in the U.S. is around that of a 1 carat diamond, and between 0.5-1.00 carat in other countries. It's interesting to note that the average size varies within the same country.

The number is inscribed on girdle of the diamond, and if found, can be looked up in order to track down who rightfully owns it. This is precisely what occurred just recently to a newly engaged couple, who, if not for these ingenious identification numbers, would have never seen their diamond again.

A 'carat' is a unit of measurement used in the diamond industry to specify the weight of a diamond. A carat is equal to 200 milligrams, so a 5-carat stone weighs 1 gram.