For many people, buying a diamond is not their everyday business. However, if you dive deeper in the world of diamonds, it appears to be difficult to make a choice. Two seemingly similar diamonds can be a world apart price-wise. The difference in price can depend on the seller. Therefore it is always more beneficial to buy diamonds straight from the source. However, the diamond prices at a diamond store can really vary as well. This is because a diamond’s value is determined by the 4 C’s of diamond valuation. The 4 C’s are: carat, cut, color and clarity. The first C to examine in this series is Carat.

Donny Explains

Our Chief Purchasing Officer helps you to understand the basics of the 4 C’s of diamond valuation. A more detailed explanation, you find below this video.

The weight of a diamond

Carat is also referred to as the weight of a diamond. All gems are weighed and the weight is expressed in carats. Carat is derived from the French word Carob. Carobs are the seeds of the fruit of the carob tree. These seeds are distributed very evenly and universal weight. On seed weighs on average 0.2 grams.

carob seeds on wooden talbe

Carat indicates the weight of a diamond. But to make it easier for customers and dealers, the carats are divided into points. One carat is 0.2 grams and 100 points. Half a carat is 50 points and weighs 0.1 grams. A quarter carat is 0.05 grams and thus consists of 25 points, and so on. This point system made it easier and clearer for both the seller and the buyer. The density of a diamond – the specific weight – is 3.2 gram per square centimeter.

The bigger the diamond, the higher the price

It is no surprise that the price of a diamond is among other things determined by size. The larger the diamond, the more the price (exponentially) rises. This has to do with rarity. Diamonds to half a carat (50 points) are the ones that are most commonly found and are therefore relatively ordinary. Diamonds of over 0.5 carats are rarer and diamonds of more than two carats are extremely rare. This causes the price to rise faster as the diamonds become bigger.

The cutting method determines the size of the diamond

The way in which a diamond is cut has a great impact on the weight of a diamond. A thick girdle (top) or belt (circumference of the diamond), can make the diamond a few points heavier. A diamond that is cut “steeper”, is heavier than a diamond that has been cut “flatter”. One should always start with assuming that the diamond is cut according to the standardized rules. According to these rules, the diamond would have a certain weight. This standard is called the “ideal diamond cut” not cut too steep and not cut too flat.

Recognizing a fake diamond based on carat

The carat can also be used to find imitation diamonds because a diamond with a given diameter has to have a certain weight. If that weight differs much from the norm, then it is probably not a real diamond, but another material.

Working tool for measuring the size of your diamond

Exponential price differences between above and below round carats

The weight also affects the price in a way that 0.99 carat is substantively worth less than a stone of 1.01 carats. This can be as much as a 15% difference in price difference. A cutter will therefore always put his best foot forward to end just above a round number. He prefers to cut a diamond 1.51 rather than 1.49 and 1.01 over 0.99. The difference between just above and below a round number causes a larger price difference than between, say, a 1.03 and a 1.01-carat diamond.

How many carats is my diamond?

Each diamond shape has a different formula to calculate the carat of a diamond. The formula to calculate the weight of a brilliant cut diamond is:

Height x diameter ² x 0.0061

This is according to the standard; a large difference is an indication of bad polishing or an imitation. Every kind of cut has its own formula to calculate the weight. So there’s a different one for emerald cut, heart shaped diamonds and a princess cut for example.

different carat sizes

Weighing a diamond with a scale

Weighing diamonds today is done with an electronic scale, formerly a mechanical. With the help of an electronic scale, weighing is a lot more accurate. It is even possible to calculate up to the 3rd digit after the decimal place. The scale that is used to weigh diamonds should be checked at least once a year by an official qualified company. Preferably, the scale is checked multiple times a year.

Diamond weighing for free

It remains always difficult to determine the weight or the carat of a diamond yourself. Therefore we encourage you to visit our store in Amsterdam. Our diamond cutters are happy to weigh your diamond for you so you will know exactly how many carats your diamond is. Combine your visit with diamond factory tour or book a Diamond Masterclass to learn everything about diamond evaluation. In the Masterclass, you will learn among other things, how to determine a diamond’s carat yourself and about the 4 C’s of diamond valuation. Read about the other C’s:

The other C’s:

> The second C, Color
> The third C, Clarity
> The fourth C, Cut

Book a Masterclass

If you want to learn everything about the craft of diamond polishing and polish a diamond yourself as well, the Diamond Masterclass is the perfect experience for you.


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