The 4 Cs was a phrase brought into the industry many years ago to help the public understand and be aware of, the important aspects of diamond buying. We will focus on these one at a time since they all play a crucial role in diamond valuation: Carat (weight), color, clarity and cut.
Carat (ct) is simply a measurement of weight in the metric system. Many confuse the other term karat as used in the U.S. for denoting gold purity, with the carat weight measurement. The carat was adopted in the United States in 1913, and today it is the international standard in most countries. The carat is defined as exactly 1/5th of a metric gram or 200 milligrams. There are about 142 carats in an ounce and about 2,272 carats in a pound. A point is 100th of a carat (or 2 mg.), which means there are 100 points in a one-carat-even stone. So if a dealer says he has a 1.37 for sale, you know it is 37/100ths of a carat over 1.00 carat.
When buying a diamond, it is very important to realize that every point must be included in the total (or net) price of the purchase. This is why diamonds sold on the wholesale level are quoted in terms of price per carat (ppc). Many dealers will assume you know this and expect you to calculate the actual net price. For example, you have a call for a 3U4 carat round brilliant with color, clarity and make (cut) that you specify. Your supplier quotes a .78 carat @ 2000. Chances are the net price on this stone is $1560.00: $2000 per carat multiplied by .78 is $1560 or 2000 x .78 = 1560. If you’re not sure, ask if it’s net or per carat. Otherwise you may be in for a disappointing loss or confusion about why a price quotation seems so high.