Carat Weight Explained

Diamond-Lighthouse-broker-stones-mini-machineOf all the four Cs of diamond grading, carat weight should be the easiest to understand, right? A diamond weighs a certain amount and that’s it. The greater the carat weight, the more the diamond will cost. Well, yes but it’s not quite that simple. Like pretty much everything else in the diamond world, it’s a little more complicated than it sounds. So how does carat weight affect the value of a diamond? And what exactly is a carat? Is it different from a karat? Or a carrot? Whether you’re selling some diamond jewelry, or you’re in the market for a new diamond, we at Diamond Lighthouse feel it’s important for you to understand each of the four Cs and how they affect a diamond’s price.


What is a carat?

A carat is 200 milligrams. Diamonds are weighed with a highly sensitive scale that reports weight to the thousandth of a carat. The weight is then rounded to the nearest hundredth. This allows gemologists to be especially precise in their measurements, and is why you’ll see diamonds listed as 0.25 or 1.07 carats. The name comes from the old practice of gem traders using small uniform carob seeds to weigh gems on balance scales. The weight became standardized and today, unlike some other measurements, a carat weighs the same no matter where in the world you are.


Karat, on the other hand, has nothing to do with diamonds or gemstones and is only used when talking about gold. Karat is strictly a measurement of how pure gold is. 24-karat gold (or 24K) is 100 percent pure gold while 18K means it’s 18 parts pure gold and six parts some other metal. Here’s where it can get confusing. The work “karat” comes from an old German coin called a mark that was made out of pure gold. The coin weighed 24 carats, so 24K became the standard by which the purity of gold is measured. So yes, “carat” and “karat” are somewhat related, but because we’re only talking about diamonds here, “carat” is the only one you should concern yourself with.


 And finally, there’s a carrot, which has nothing to do with either diamonds or gold, but is an orange root vegetable that may or may not be good for your eyesight. It’s quite tasty.


So how does carat weight affect the price of my diamond?

For the most part, carat weight affects a diamond’s value pretty much how you’d expect it to. All other factors being equal (clarity, color and cut), the higher a diamond’s carat weight, the more valuable it is. Things start to get complicated when you hit what the industry calls “magic sizes.” Magic sizes are the points where the diamond sees a significant jump in per-carat price. The magic sizes occur every 0.25 carats starting at 0.5 carats. (E.g. 0.5, 0.75, 1.00, 1.25, etc.) If you know this information, you can use it to your advantage when buying a diamond. For example, there won’t be any visible difference between a 0.99-carat diamond and a 1.00-carat diamond, but the 1.00-carat diamond will be much more expensive. That’s because the per-carat price of the diamond increases significantly at the 1.00-carat mark.


This information is also handy when you’re trying to sell a diamond that has a scratch or inclusion. These can sometimes be removed or repaired by polishing or cutting, but before making the decision, you should know your magic sizes. Make sure that removing the flaw won’t bring the carat weight down below one of them, otherwise the value could end up being much lower than it would have been if you’d left it alone.


The good news is if you’re selling your diamond jewelry through Diamond Lighthouse, you don’t have to worry. Our expert gemologists know exactly how to get you the most money for your diamonds. They’ll only repair a scratch or inclusion if they’re absolutely sure it will increase the value and have your permission. At Diamond Lighthouse, we do all the work for you, from evaluating your diamond, to figuring out the best way to sell it, to finding an expert buyer willing to give you the best price. Our unique process guarantees you more money for your diamonds than you’ll find anywhere else. Contact Diamond Lighthouse today.



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