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When considering the four Cs of diamonds, it is carat weight that has perhaps the most romantic beginnings. In the sun-drenched soils of the East Mediterranean there grows the Carob tree, noted for its edible pods and use as a chocolate substitute.

When early gem traders required a set unit of mass to determine the weight of a diamond, they observed the fairly uniform size and weight of the Carob seeds. With each evergreen pod containing a fistful of seeds, the traders were never short of nature’s measuring weights and began using them as standard practice for counterbalancing diamonds. Interestingly thought, modern weighing techniques have found carob seeds to be as inconsistent as any other species in their weights.

Today, we use the word ‘carat’ to describe diamond weight. One carat is equivalent to 200 mg (0.00705 oz), and is used as a standard for diamond companies the world over. So why is diamond carat important?

Carat weight is the most universally constant feature of diamonds, in that it’s not a feature that can be viewed subjectively. Anyone with a good quality scale can measure the carat weight of any diamond. Granted, that scale will have to be able to measure incredibly minute differences in weight.

I was once told a bit of advice that has stuck with me:

“If you want to compare diamond value by how much they way, you might as well compare the value of paintings by how big they are.”

Imagine valuing the Mona Lisa just based on its size—it’s not an act that will bring an accurate valuation. Van Gogh’s Starry Night will be more valuable than a larger piece by an unknown artist because we value art through more important features than size. That being said, it’s worth knowing that size does increase the price tag, but not necessarily the quality.

The History of the Carat

The word ‘carat’ apparently entered the English language in the 15th century. It’s etymology is a unique look into how words were borrowed and changed over time, as the English ‘carat’ comes from the Italian carato, which in turn comes from the Arabic qīrāṭ. This word was taken from the ancient Greek kerátion, which means ‘carob seed’.

Diamond Standardization

‘Carat’ is not to be confused with the term ‘karat’ (which refers to the purity of gold), and has always been used to refer to a specific weight. Today, each carat is divided into 100 points. For example, a 20-point diamond would be measured as 0.20 carats.

A single carat is defined as 0.20 grams; therefore, a 100-carat diamond would weigh 20 grams. While the numbers can be a little confusing, gram weight has little bearing when purchasing a diamond. Carat weight is what counts. But it hasn’t always been this way.

Only in 1871 was a standard weight for a carat proposed, at 205 milligrams, by the Syndical Chamber of Jewellers. This standard was accepted six years later in Paris. However, many other countries preferred using 200 milligrams as the standard, as it was exactly one fifth of a gram and therefore easier to work with.

At the General Conference of the Metric Convention, held in Paris in 1907, this new definition was accepted unanimously.

How Big is A One-Carat Diamond?

As carat refers to weight, the size of a one-diamond carat really depends how a rough diamond has been cut. That being said, you will usually find that a one-carat diamond measures around 6.5mm in diameter. Below you’ll find a useful table for comparing weights and average sizes.

One thing that is interesting to note is that a doubling in carat weight does not equate to a doubling in the diameter of the diamond.

Where to Find the Best Diamonds

For the highest quality diamonds I would recommend contacting Whiteflash, as they have a very knowledgeable GIA & AGS accredited team and the largest selection of in-house super ideal cut diamonds.

However, if you’re looking for less expensive diamonds (with lower quality), Blue Nile is the place to shop. They’re known for being pioneers of online diamond sales and have one of the largest ranges of available diamonds in the world.

Carat Price: How Much is a One-Carat Diamond Worth?

While it is reasonable to assume that bigger is better, when it comes to diamonds, this is certainly not the case. In fact, when valuing a diamond, carat weight has arguably the least impact on the price.

A diamond with a high-carat weight that is heavily included (as in contains internal blemishes) or discolored is far less desirable than a smaller, clearer stone. A two-carat diamond ring may have a great impact from a distance, but if it is badly cut it will look no brighter than glass on the hand.

Opting for a higher carat weight and sacrificing cut, color, and clarity will greatly alter the appearance and worth of a diamond and in some cases, may even compromise its durability.

Diamonds of 1.50 carat and below are used in most fine jewelry, with high clarity and color stones above this weight considered rare masterpieces. For some, however, size really does matter.

If your budget allows, high-quality diamonds above two carats make truly spectacular pieces of jewelry. While commanding a higher price, they are examples of the masterful craftsmanship of man and the beauty of Mother Nature.

The bottom line is that size is not everything in the world of diamonds; a small twinkling star will always attract more attention than a large dull stone.

Does Diamond Carat Matter?

My opinion? Not really. I’d always take a one-carat IF D Ideal Cut diamond over a two-carat SI2 K Average Cut diamond.

Ask yourself this—when you look at a diamond, what is the first thing you notice? 99 times out of a hundred the answer will be how brilliant the diamond is, how much it sparkles. Only the smallest amount of people are looking at size, which is probably the biggest vanity metric there is, and doesn’t contain any of the substance or quality that makes diamonds beautiful.

This is especially true when the diamond has been used in jewelry or is surrounded by other diamonds. Plus, the only part of a diamond you really see is the table (the top surface) and, if you’re lucky, you’ll be distracted by how brilliant the diamond is and how much fire it’s giving off.

My Final Thoughts on Diamond Carat

Saving money on diamonds is complex, but there are ways and means. If you want to choose the biggest diamond you can afford, combine that choice with the lowest clarity and color gradings that still look good to the naked eye. A 1.5-carat diamond with VS2 clarity and H-color will most likely still look great, provided it has a good cut and is eye-clean.

Cut and eye-cleanliness are potentially the most important qualities you need to look for. Remember that a diamond with a poor cut will actually look smaller compared to a diamond of the same size, due to the low level of light performance it produces.

Exploring the Four Cs of Diamonds

Diamond carat is only one of the all-important Four Cs that influence both the price and the quality of a diamond. To make the most of the diamond-buying experience and get the most diamond for your budget, it’s well worth getting to grips with the other Four Cs that make such an impact on even the smallest diamond.

You can read about the other three Cs here: