Diamonds - The 4 Cs
A diamond's value is based on four factors:
Carat weight refers to the size of the diamond. The other three qualities describe the gem’s quality.
One way to think about the 4Cs is to imagine a seesaw, with size (carat weight) on one end and quality (the other three Cs) on the other. Within a given price range, as size increases, quality must diminish. If quality improves, size must diminish. In other words, you can either spend more per carat for a higher-quality stone, or you can get a larger stone and settle for lower overall quality.
Everyone talks about carat weight. Familiarize yourself with the importance of the other 3 Cs (especially cut proportions!) before you go shopping.