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If you’ve spent time looking at engagement rings and other diamond jewelry online, you may have noticed the acronym “CTTW” alongside other important details such as cut, clarity, color and carat weight.
For example, these are beautiful diamonds for a 2.18cttw pair of earrings from Blue Nile. That means they are 2.18 carats combined. Or you can look at this very elaborate and ornate halo setting for an engagement ring also from Blue Nile. There are 3.07 carats worth of accent diamonds on this ring. If you put a 1ct center diamond into this ring, you will have a 4.07 cttw engagement ring.
CTTW stands for “carat total weight,” or “total carat weight.” It’s a metric that’s used to measure the total weight of all of the diamonds in a specific piece of jewelry, such as a tennis bracelet or a pavé diamond ring.
You might see “CTTW” written as “CT TW” for some engagement rings. CT stands for “carat,” a unit used to measure a diamond’s weight. TW is short for “total weight” and is used to measure the total weight of all diamonds in a piece of jewelry.
The carat weight of one diamond and the total carat weight of a diamond ring are very different numbers — a fact that can cause some confusion for first-time buyers. Below, we’ve explained how CTTW works, as well as how it differs from other measurements of a diamond’s weight.
As we covered in our guide to diamond carat weight, the carat weight of a diamond refers to the amount the diamond weighs, not its size. A diamond of a single metric carat weighs exactly 200 milligrams and can range in diameter from 5.60mm to 6.60mm depending on its cut grade.
Carat weight is abbreviated at “ct.” When you’re viewing loose diamonds online, you’ll generally see their carat weight listed alongside factors such as cut, color and clarity.
CTTW, on the other hand, refers to the total weight of all of the diamonds in a specific piece of jewelry. Unlike ct., which is used to show the weight of a loose diamond or center stone, CTTW is only used to display the total carat weight of all diamonds.
If you’ve read any of our other guides, you might have also seen the acronym “CTW” used to refer to total carat weight. Both CTTW and CTW are used worldwide and have the exact same meaning.
Many engagement rings only contain one center diamond. For example, this knife edge solitaire setting from James Allen is designed to only hold a center stone. As a result, the ring’s total carat weight (CTTW) will be the same as the carat weight of the center stone.
Other rings, such as this lotus basket pavé engagement ring from James Allen, have a band that’s lined with small diamonds. This specific ring features 36 small round diamonds, adding up to a total carat weight of 0.25 carat without a center stone.
The total carat weight, or CTTW, of this ring is calculated by adding together the carat weight of the pavé set diamonds and the weight of the center stone. For example, by selecting this 1 carat round H VS2 diamond from James Allen, the total weight of the setting and center stone is 1.25 carats.
Some engagement ring settings can have a significant total carat weight even before the center stone is added. For example, this grande halo split shank setting from James Allen has a 0.70 CTTW without any center stone due to its 64 pavé and halo set diamonds.
The price of a diamond increases exponentially with its carat weight. For example, a sells for $1,243. A 1.00 carat diamond with the same specifications costs $5,453, despite only being twice the carat weight.
The reason for this is simple. Large diamonds are significantly rarer than smaller diamonds and as a result, they can command higher prices on the market. Because of this, a large diamond is always going to be worth significantly more than a smaller diamond of the same quality.
This isn’t the case with a ring’s total carat weight. Because this figure is made by adding up the carat weight of all of the ring’s small diamonds, there isn’t an exponential relationship between the ring’s total carat weight and its value.
For example, mounted in this solitaire setting from Blue Nile, the 1.00 carat H color, VS2 diamond above costs $5,673 in total. This ring has a total carat weight of 1.00 carat.
Meanwhile, with this 0.50 carat H color, VS2 diamond is available for $2,763. It also has a total carat weight of 1.00 carat.
This means that if you’re on a limited budget, a pavé or halo setting with a fairly high total carat weight but a small center stone could be a good idea. While you won’t get the full wow factor of a large center stone, a ring of this type can look beautiful and elegant, all at a lower cost.
The carat weight of a diamond — or, in this case, the total carat weight of a ring — is only one of several factors you should consider when you’re choosing an engagement ring.
Other factors, such as a diamond’s cut, color and clarity, also play a role in its appearance and value. Known as the 4 Cs, these factors all interact with each other to affect the way a diamond looks and the amount you’ll pay for it.
We’ve covered these in more detail, as well as what you should look for, in our guide to buying a diamond.
CTTW, or total carat weight, always refers to the total weight of all diamonds in a ring, bracelet, earrings or other pieces of jewelry. When you’re viewing a setting on its own, it’s the weight of the halo or pavé diamonds. For a complete ring, it’s the weight of all small diamonds and the center stone.
Carat weight, which is abbreviated as ct, cw or CW, only refers to the weight of the center stone on its own.
While a ring with a large total carat weight can look impressive, it’s important to remember that the weight of the center stone is usually the biggest factor in determining an engagement ring’s value.
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