diamond clarity, diamond loupe

Diamond carat: What you need to know

If you’re looking to buy a diamond engagement ring, diamond carat is one important detail that you need to understand. It is a key factor in determining the rarity of the diamond and it’s price as a result.

Diamond carat, very often denoted as ct for short, is one of the diamond 4CsIt is the international unit that quantifies the weight of a gem One carat is equivalent to a fifth of a gram or 0.20g.

The metric carat is divided into 100 points. So a one carat diamond is quantified as 100 points, while half a carat is equal to 50 points.

The origin of the word comes from the Greek word for carob bean, which also means small weight. Interestingly carob beans are very uniform in size. For this reason, gem traders used these beans as a counterweight to balance their scales. 

Although it makes sense to equate weight and size, diamond carat is not the same as its size. This is because the diamond cut also affects the size of a diamond. A diamond can be cut too deep or have a very thick girdle. This means that extra weight lies in the lower part of the diamond, which is not visible when the diamond is set in the ring. For instance, a poorly cut 1.20ct diamond could appear the same size as an optimally cut diamond of 1.00ct. The result is paying for a larger diamond with no added benefit. This is where the diamond cut, as well as it carat, becomes important.

diamond carat vs size

Simply put, the larger a diamond is, the bigger its rarity. Nature produces far more smaller size diamonds than diamonds that are bigger than one carat. Naturally, the rarer a diamond is, the higher its financial value.

Due to their rarity, large size diamonds command a premium. In fact, the difference in price is not a linear one, but exponential. This means that a 1.00ct diamond costs much more per carat than two 0.50ct diamonds. Similarly, a 2.00ct diamond has a much high price per carat than a 1.00ct diamond.

If budget is not an issue, one would pick a stone with exceptional colour, clarity, cut and carat. In reality, most people prioritise the diamond 4Cs and pick the “C” that is most important to them. Often, this isn’t the diamond carat.

A larger diamond doesn’t always mean a beautiful diamond. In other words, a diamond also has to have lots of brightness, fire and sparkle. These qualities are a result of its cut, rather than its carat.

In addition to the cut, colour and clarity play a very important role in emerald cut diamonds. These elegant stones have long rectangular facets that do not hide inclusions extremely well. This step cut style also has less scintillation (sparkle). For this reason, a high grade colour becomes especially important.

A diamond engagement ring is an emotional purchase, as well as a financial investment. When purchasing your diamond ring, it is advisable to always get a diamond report that certifies its carat.

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