How to Use Carat vs Karat to Describe Diamonds and Jewelry

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June 8

Diamond Carat vs Karat Gold are terms that describe weight expressions in parts per hundred and thousand, respectively; e.g., 1.00 carats; and 18 karat is 750/1000.

A metric carat is a unit of mass equivalent to 200 milligrams or 0.00643 troy ounces. We express karat gold by the percentage of content proportional to parts per thousand, e.g., 750 parts gold is 18 karat.

In other words, the terms carat and karat are as different as diamonds and gold. In that case, use the phrase carat to describe gemstones in carats and karat to describe gold content.

Diamond Stud Earrings Carat Weight Size Reference Chart.

Reference Carat Weight Brian Gavin Diamonds.

Although there are distinct differences between carats vs. karats, they sound the same. That might not be very clear when you first start shopping for a diamond engagement ring.

Knowing the difference between Diamond Carat vs Karat Gold ensures that your local jewelry store clerk takes you seriously. On that note, it's essential to know that the abbreviation for diamond carats is ct. and cts.

In contrast, the abbreviation for gold content includes 10k, 14k, 18k, 22k, or 24k pure gold. You'll find a cross-reference below that defines the gold content in parts per thousand for the standard expressions of karat weight.

Expressing Diamond Carat vs Karat Gold:

Professionals in the jewelry industry commonly refer to diamond carat weight as points, e.g., a 0.75-carat diamond weighs seventy-five points. Consequently, there are one hundred points per carat, just as there are one hundred pennies to a dollar.

Diamond Carat vs Karat Gold, BGD Signature Blue.

1-carat Brian Gavin Blue Fluorescent Diamond.

We use scales developed explicitly for the diamond industry to weigh diamonds that express the carat weight to the third digit. For example, the carat weight of this Brian Gavin Signature diamond is 1.000 carats.

You could also express the weight one hundred points, but nobody in the industry would ever say that. Instead, we would say that it's a 1-carat diamond or weighs one carat.

It also exhibits medium blue fluorescence, so it's glowing blue in the photograph. Consequently, it will look perfectly normal (white) unless you expose it to black light.

Trade members are likely to describe diamonds weighing less than 1.00 carats by carat weight points. For example, this 0.928 carat, Brian Gavin Signature diamond weighs ninety-two points.

Some people in the diamond industry might round the carat weight up to ninety-three points. Alternatively, another person might round it down and describe it as a ninety-pointer.

Ways to Say 1-carat:

If you are shopping for a 1-carat diamond, you could say that you are shopping for a one-carat diamond. However, if you were shopping for a diamond weighing between 0.90 – 0.99 carats, you might say that you're looking for something around ninety points.

Halo Diamond Stud Earrings by James Allen.

Halo Diamond Studs by James Allen.

Alternatively, you could say that you are shopping for a 0.90 - 0.99 carat diamond. Whereas if you are shopping for a diamond weighing a little more than a carat, you would say just that.

For example, this 1.10 carat, I-color, VS-1 clarity, Brian Gavin Signature diamond weighs a carat-ten. Alternatively, you could say that it weighs one carat and ten points or one hundred and ten points.

Express the carat weight of diamond stud earrings as the combined weight of both diamonds. Under those circumstances, one-carat total weight diamond earrings consist of two half-carat diamonds.

Diamond Carat vs Karat Gold vs Carrots:

Carrots vs Diamond Carats vs Karat Gold.

Carrots vs Diamond Carats vs Karat Gold.

No article on diamond carat weight or karat gold would be complete without a bunch of carrots. You had to know that I was going here. Right?

Carrots are available individually or in bunches, whereas diamond carats come in parcels. If you're buying a large parcel of diamonds, you might say that you're buying a business.

If we're talking about diamonds in a crowded restaurant, we'll refer to them as puppies because we don't want to be followed home and killed in our sleep.

For example, I might say something like, "I recommend you buy this puppy from Brian Gavin; it's a 1.132 G, VS-1," and leave you to fill in the blanks. Consequently, the word "Puppy" is more of an in-house term not used by the diamond industry.

So don't walk into a jewelry store and ask to see some puppies because they might not understand. It's more likely that the clerk will stare at you with a blank look of confusion. Oh wait, they're probably going to do that anyway.

If you think I'm kidding, read about my experience with Secret Shopping Tiffany & Co. But I digress, so let's get back to the differences between Diamond Carat vs. Karat Gold.

How to Express Diamond Carat Weight In Points:

While people think of diamond carats as whole numbers, we express them in points. In contrast, most consumers describe diamonds by what is commonly known as the magic marks:

  • Quarter Carat.
  • Third Carat.
  • Half Carat.
  • Three Quarter Carat.
  • One Carat.

The carat weight might also be expressed as 0.25 / 0.33 / 0.50 / 0.75 / eighty points, ninety points, zero-point ninety to ninety nine points, etcetera.

Consequently, a diamonds' Price Per Carat (PPC) may increase substantially at those magic marks. In other words, the price per carat increases between 0.99 and 1.00 carats, as shown below.

Diamond Price Per Carat:

The price per carat (PPC) of this "zero-nine-two-eight carat" 0.928 carat, I-color, VS-2 clarity, Brian Gavin Signature round diamond is less than the PPC for this "one-oh-seven-one carat" 1.071 carat, I-color, VS-2 clarity, Brian Gavin Signature round diamond.

As noted previously, a substantial increase occurs between the 0.99 – 1.00 carat marks. Price increases occur at different carat weight ranges, such as between 0.49 – 0.50 carats, 0.69 – 0.70 carats, 0.89 – 0.99 carats, 1.49 – 1.50 carats, etc.

There are also price differences in the PPC caused by diminishing discounts offered at the wholesale level for volume dealers. Those discounts may reflect demand for higher carat weights or difficult-to-find sizes.

Rapaport Diamond Report price list, May 2019

Diamond Prices Per Carat.

The discount off the Price Per Carat for this 1.330 carat, I-color, VS-2 clarity, Brian Gavin Signature round diamond ($7,945.00 per carat) will be less than the 1.071 carat from above ($7,228.75 per carat).

The reason is that the larger diamond is further from the 0.99 – 1.00 carat marks and closer to the 1.49 – 1.50 carat marks. Consequently, the PPC of larger diamonds is higher than for diamonds that weigh less within each price tier.

For example, the PPC on the price guide for round diamonds weighing between 1.00 - 1.49 carats appears to be the same. To be clear, we're referring to the price stated for each combination of clarity and color. 

However, hidden price increases and discounts depend on diamond cut quality. Additionally, less obvious factors such as inclusion type, location, extent, and fluorescence contribute to pricing.

How Diamond Cut Quality Influences Price:

The degree of diamond cut quality can affect diamond prices by up to sixty percent. Let's say that the wholesale list price of a diamond is 10,000 per carat.

If the proportions and overall cut quality of the diamond are poor, then the actual price of the diamond might only be 4,000 per carat. While if the proportions and overall cut quality of the diamond are very good, it might be 10,000 per carat.

Black by Brian Gavin Diamond Prices.

Black by Brian Gavin H&A Diamond.

Consequently, most diamonds are only very good in overall cut quality. The price per carat of super ideal cut diamonds is usually higher than the Rap list price.

That means that hearts and arrows diamonds cost more than standard ideal cut diamonds. As they should since it can take up to 4X longer to produce a higher degree of optical precision.

The upside is that better optical precision produces more virtual facets within the diamond. The upside is that it creates a more significant outward bound sparkle that is also more vivid and intense.

Karat Gold Breakdown:

24k Pure Gold contains twenty-four parts pure gold and does not contain any other alloys. Consequently, 24k jewelry is very soft and lacks durability, so most commercial jewelry is 10k, 14k, 18k, or 22k gold.

In that case, the gold is mixed with other alloys to make it more durable and change the color. Gold is commonly combined with other alloys to change it from yellow to white, pink, or green.

Consequently, yellow gold, white gold, and rose gold are the most common types of gold used for jewelry. Here is the gold content for the most common jewelry alloys:

  • 24k gold is pure gold; it consists of twenty-four parts pure gold.
  • 18k gold is 75% gold, consisting of eighteen parts gold and six parts other alloys.
  • 14k gold is 58.3% gold, consisting of fourteen parts gold and ten parts other alloys.
  • 10k gold is 41.6% gold, consisting of ten parts gold and fourteen parts other alloys.

European Gold Alloy Stamps:

Units of Karat Gold are expressed differently in Europe, where they describe gold purity as parts per thousand. Thus European jewelry is likely to feature a gold content stamp in a numerical format:

  • 1000 (parts per 1000) = Pure Gold.
  • .999 = 99.9% Pure Gold.
  • 916 (parts per 1000) = 22% or 22k gold.
  • 750 (parts per 1000) = 75% or 18k gold.
  • 625 (parts per 1000) = 62.5% or 15k gold.
  • 585 (parts per 1000) = 58.5% or 14k gold.
  • 500 (parts per 1000 = 50% 0r 12k gold.
  • 416 (parts per 1000 = 41.6% or 10k gold.
  • 375 (parts per 1000) = 37.5% or 9k gold.
  • 333 (parts per 1000) = 33.3% or 8k gold.

In that case, a piece of white metal jewelry stamped 925 would be silver jewelry with a sterling silver content of 92.5%. Similarly, the alloy content of Platinum jewelry appears in parts per thousand, such as PT, PLAT, PT900, or PT950.

Manufacturer Gold Hallmark Stamps:

James Allen Diamond Engagement Ring Reviews.

James Allen Diamond Engagement Ring Reviews.

Jewelry manufacturers are not required to stamp the alloy content of a piece on the item. However, if they stamp the alloy content on the jewelry item, they must also indicate their hallmark.

A hallmark is the registered mark or identification of the manufacturer. This practice aims to prevent "under-karating," which is the practice of stamping a ring or jewelry item with a karat stamp, indicating a higher gold content than what the piece contains.

An instance of under-karating was investigated in 2002 by a joint task force comprised of the Nassau County District Attorney's office and the Jewelers Vigilance Committee.

Six businesses failed the karat test. They were each issued two violations—one for deceptive practices and one for unconscionable trade practices per sale. Consequently, companies face fines of up to $2,500 for a first violation, then it jumps up to $4,000 for a second violation.

The fines continue to increase up to $5,000 for each additional violation. That means that for a store where investigators purchased eight items that all failed a karat test, the fines could be as high as $76,500.00

The Stamp Inside the Ring:
Brian Gavin Hallmark Stamp Inside Ring.

Brian Gavin Hallmark Stamp Inside Ring.

This photograph of the Classic Truth Solitaire by Brian Gavin shows their hallmark stamped next to the alloy stamp of PT 950.

Thus when you look at the inside of the ring shank, you know that Brian Gavin manufactured the ring. In addition, it's also easy to see that the ring is 950 parts platinum per thousand or 95% pure.

Legitimate jewelry manufacturers such as Brian Gavin purchase casting shots produced by companies specializing in formulating specific alloy mixtures for jewelry production.

Using a commercially refined casting shot ensures that the alloy content of each piece of jewelry produced will be as it is supposed to be. Larger refining companies use state-of-the-art processes to ensure accurate weights and measures.

In contrast, smaller operations, such as jewelers who melt down old gold and try to refine it themselves, are not likely to produce accurate results. Another problem with using old gold instead of casting shot is that it's prone to air bubbles that cause pits and brittleness.

I hope that this explanation that focuses on the differences between Diamond Carat vs Karat Gold was helpful and that you enjoyed reading it. Feel free to take advantage of my free Diamond Concierge Service if you would like help finding a diamond or if you have any jewelry questions.

About the Author

Dive deep into the glittering world of diamonds with Todd Gray, the CEO of Gray Matter Development, LLC. Todd has 35+ years of experience as a diamond buyer and trade consultant. He ghostwrites content for several online vendors and is an avid Freediver, currently exploring the Cenotes of Yucatan, Mexico. Dive into brilliance with Todd Gray!