Lab-Grown Diamond Carats – What you need to know before buying

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Diamond carats are probably the most misunderstood aspect of diamonds. It does not refer to size but rather weight, and the two are not always similar. This is due to differences in cut, shape, and depth. Two diamonds with identical carats may measure differently across the diamond surface (the visible part when set in the jewelry). And while the size and weight tend to be correlated, there is more to diamond size and quality than carat.

This is the case for both lab-grown diamond carats and mined diamonds – because, as you will know, lab-created diamonds and mined diamonds are exactly the same (except for the negative impact of the mining operation).

So why not just use the imperial or metric system? According to GIA, the leading diamond grading laboratory and the inventor of the 4Cs, carats are historically based on the weight of carob tree seeds used in the early diamond trade as counterweights on balance scales, and the system has stuck.

It does add to the mystic aura of diamonds and perhaps fits well with the historically closed diamond trade. It probably wouldn’t sound as romantic to announce your 0.021-ounce engagement ring.

1 diamond carat is equal to 0.007 ounces or 0.2 grams. About the weight of a paper clip, according to GIA.

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Why you should care about lab-grown diamond carats

While diamond carats are definitely not the only aspect you should care about (read about the other 4Cs), the carat has the biggest impact on price and is usually (and wrongly) the only feature people refer to when showing off their rock. It is also the only truly objective measure of the 4 Cs (because you can put it on a scale).

The carat you end up with is often determined by your budget and criteria for diamond cut, diamond clarity, and diamond color. For example, with a diamond budget of $1000, you can adjust the cut, clarity, and color to see how many carats you can get for your diamond buck.

You can get advice on which of the 4Cs is more important (it’s the cut!) and suggested grades in our lab-grown diamond buying guide. So when you have decided on cut, clarity, and color, the carat weight of available diamonds can be easily found to fit within your budget.

One thing to note is that a lower-carat diamond can actually look bigger and, not least, more impressive than a larger one if the cut, clarity, and color grades are higher. Combined, they determine the sparkle, and that’s the unique and sought-after hallmark of diamonds.

Our top-rated jewelers for the most diamond carats for your budget

Compare lab-grown diamond carat weight

GIA has made a handy comparison widget that you can try yourself below or on GIA’s website here.

Total carat weight

Note that when buying a pair or several diamonds, the seller will often refer to the total carat weight and not the individual carat of the diamonds. Make sure that you have both specified so you know exactly what you are paying for.

Buying tips!

Consider going for a lab-grown diamond carat weight just below the standard sizes of 0.25, 0.50, 0.75, 1.0 carats, etc. You often pay a premium to reach those thresholds (probably so you can tell people you have a full-carat diamond, for example). You can get a better deal going for a 0.96-0.99 carat, and you would not be able to tell the difference in size anyway.

The shape of the diamond also impacts the carat – or perhaps rather, price. The reason is two-fold. First, different diamond shapes result in different surface areas and sizes using the same carat weight. That is because of how they are cut. Second, shapes other than the brilliant round cut typically cost less but can appear bigger (because of #1).

Lastly, take into account what the diamond is going to be used for. For example, a diamond in an earring setting may appear larger than on a pendant. A diamond in a ring setting will appear larger on a small finger compared to a large finger. A smaller band makes the diamond look bigger than a larger band would. A diamond surrounded by smaller diamonds in a halo setting will appear larger.

Why are high carat diamonds so much more expensive?

Carat and price do not follow a linear relationship. That is, a 10% heavier (higher carat) diamond does not cost 10% more. Usually, a 10% increase in carat leads to more than a 10% increase in price. Why? Because higher-carat diamonds are cut from larger, heavier stones, and those are rarer. So while there are lots of small raw stones to cut lower-carat diamonds from, there are increasingly fewer available stones to cut high-carat diamonds from.

As a rule of thumb, if you double the carat, you pay four times as much for the diamond.

Are lab-grown high carat diamonds cheaper than mined diamonds?

Lab-grown high-carat diamonds are typically at least 60-80% cheaper than mined diamonds. However, very large diamonds are still not grown in laboratories. So if you are looking for a million-dollar diamond, you’ll be hard-pressed to find one that is lab-created.

However, 99% of diamond shoppers are not, and they will be able to save a lot by choosing a lab-grown diamond while also saving the environment and doing society a favor.

How much are different lab-grown diamond carats?

As noted, prices for lab-grown diamonds vary by weight and quality. For the same quality, the price will go up exponentially as the weight increases due to rarity and production complexity.

But if you are wondering exactly how much the different lab-grown diamond weights cost, we have the answer. We track lab-grown diamond prices and update them monthly. See April 2024 prices for the most popular diamond carat weights below.

Should I buy high-carat lab-grown diamond jewelry?

In short, yes! You can easily find high-carat lab-grown diamonds that are cheaper, socially, and environmentally more friendly than mined diamonds. All while being exactly the same in every other way.

Megan Markle, a (former) royalty, is able to find fitting lab-created diamond stones for her jewelry, so most likely, we are too.

We recommend you follow our step-by-step buying guide to lab-grown diamonds. Read our reviews of lab-grown diamond sellers or skip ahead and visit our highest-recommended lab-grown jewelers Clean Origin, Grown Brilliance, Ritani, Brilliant Earth, and James Allen.

Our top-rated jewelers for the most diamond carats for your budget

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Rolf Hartmann
Rolf Hartmann

Rolf Hartmann has decades of experience in the jewelry industry. He knows everything you need to know to find the perfect diamond. He's an expert in lab-grown diamonds and has followed the exciting development of lab diamonds from industrial usage to the incredible gemstone quality that lab-grown diamonds are today. Rolf guides you to find the right diamond at the best possible price and expertly and transparently reviews all lab-grown diamond sellers.

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