The 4Cs, are the globally accepted standard for assessing the quality of a diamond —color, clarity, cut and carat weight.

On average, the retail price for one carat diamonds can be anywhere between $2,000 to $16,000, and between $8,000 to $72,000 for two carat diamonds . And of course, the retail price and the resale value of a diamond are very different things.

The carat is the standard unit of measurement for diamonds. Although most people think of a carat as a size, it's actually a weight. One carat is equivalent to 0.2 grams. A 1 carat diamond is about 6.5mm in diameter on average.

A carat is a unit of measure for the weight of gemstones, as in an eight-carat diamond or The jewel is 1 carat. In the US and other places, the word karat is typically used as a unit of measure for the purity of gold, as in 14-karat gold and 24-karat gold.