People often mistake carats as a measurement of size, but they actually measure approximate weight (CTW = Carat Total Weight). Typically, a heavier diamond appears larger, but size isn't everything. Two diamonds of equal carat weight can have significantly different value when the other Cs are considered.

Like any rock or mineral, diamonds can have flaws. Choosing a diamond with a difficult-to-detect inclusion or blemish can be a great way to save on cost without sacrificing beauty.

The GIA Diamond Clarity Grade scale has 11 grades in all. Most jewelry stores carry VVS as their highest grade. VS or SI are considered by most to be "fine quality" diamonds.

Diamonds come out of the earth in many different colors. The market has traditionally valued white diamonds higher than others, and the grading scale offers five groups of 23 letters to reflect that.

Cut refers to a stone's shape, facet, and polish. Sometimes diamonds are cut so they're heavier, fetching more value for their carat weight. Sometimes they're cut to hide or minimize inclusions by expert diamond cutters skilled at bringing the brilliance out of each diamond they work with.