Diamond Information: Carat Weight

Of all of the "four Cs" consumers use to evaluate diamond jewelry, Carat Weight could be the most important one to consumers. The term Carat Weight applies to how much the actual stone weighs. The more Carat Weight, likely the more expensive a stone will be. Of course, an overall stone's value can be impacted by other factors such as Color, Clarity and Cut. The Carat Weight, though, will be the predominant factor as you set a budget and begin searching for a stone because it will affect most of a stone's value and price.

Rarity of stones

One of the reasons that carat weight will affect value is that diamonds are rare. A diamond that weighs 2 carats is estimated to be three times as valuable as a similar 1-carat stone. When someone says their diamond ring is one in a million, the saying could be accurate - a 1-carat diamond accounts for one of every million diamonds that are mined. If you're lucky enough to own a 2-carat diamond, it's even more rare: only one out of every 5 million diamonds that are mined is 2 carats. This is one of the reasons why these larger stones are so expensive. There just aren't that many available when compared with other sizes of diamonds.

What "carat" means

A carat is a unit of measurement for stones. One carat is equal to one-fifth of a gram (or .20 grams). That means that a 5-carat stone weighs 1 gram. Carats are further broken into a point system in which there are 100 points to a carat. So if you find a stone that is 25 points, that means it is one-quarter of a carat. One carat also equals 200 milligrams, and you'll need 142 carats to equal a single ounce.

Facts and figures

Jewelry terminology can occasionally be confusing. It's important not to confuse the term "carat" with "karat." These are two very different things. The term "carat" is derived from the carob seed, which in antiquity was used as a way to ascertain the weight of precious gemstones. The term "carat" as we know it today has been around for nearly a century. "Karat" is the unit of measurement for gold.

As diamonds are rare - after all, a 2-carat diamond accounts for only one of every 5 million diamonds mined - it may be surprising to learn that the largest diamond ever mined weighed 3,106.75 carats. Called the Cullinan diamond, this stone - which weighed a shocking one and one-third pounds) was mined in 1905 in South America. It was broken into several stones and some of them are part of Great Britain's crown jewels.

The average diamond engagement ring sold today is sized from one-half to three-quarters of a carat. Remember that the carat weight is not the only factor in a diamond's value - the color, clarity and cut also will impact its overall beauty and cost.