What does “total carat weight” mean on a jewelry listing?

ZKZ Editorial TeamMain answer · Product & gemmology desk

Total carat weight (TCW, also written ctw or cttw) is the combined weight of all the diamonds in a piece. It is not the size of one stone. A 1.00 TCW pendant can hold one small centre stone plus many tiny ones, while "1 ct" on its own may refer to a single stone. Always ask for the centre stone's weight as well.

What the figures mean

Fact A carat is a unit of weight equal to 200 milligrams, and a point is one hundredth of a carat. The FTC Jewelry Guides say a diamond's weight must not be misrepresented, and that a figure given in decimals should be accurate to the last decimal place. So ".47 carat" should be accurate to the second decimal, and ".5 carat" should fall between .495 and .504 (16 CFR 23.18).

Fact If weight is given in fractions, such as 1/2 carat, the FTC says it can represent a range, and the seller should conspicuously disclose that the weight is not exact and give the range or tolerance used.

Fact GIA's carat-weight guidance describes TCW in the same way: the combined weight of all diamonds in the piece.

Why two "one carat" pieces can differ

Our advice Weight is not size. A single 1.00 ct stone and ten 0.10 ct stones add up to the same TCW, but they look different, cost different amounts and behave differently when worn. Per-carat price also usually rises with stone size, so a piece made of many small stones is normally cheaper for the same TCW.

Our advice Weight also does not say how the stone is cut, how well it is graded, or whether it is lab-grown or mined. Two stones of the same weight can differ in diameter.

What to ask

• What is the weight of the largest (centre) stone, and how many stones are there in total?
• Is the weight measured or an estimate? Is the figure rounded?
• Does the TCW include only diamonds, or also other stones?
• For earrings, is the TCW for the pair or for each earring?
• Is there a report or inscription for the main stone?

Uncertain Industry practice on rounding and on how "TCW" is shown varies between sellers, and the FTC Guides are US guidance. If the listing is vague, ask for the number of stones and the size of each in writing before you compare prices.

Related reading: Eternity Band Carat Weight: What You Get at Each Size · Tennis Bracelet Carat Weight and Fit: What to Expect

Sources

• 16 CFR 23.18, FTC Jewelry Guides: misrepresentation of weight and "total weight"
• FTC, In the Loupe: Advertising Diamonds, Gemstones and Pearls
• GIA 4Cs, Nine things about diamond carat weight

Fact = stated by the cited source. Our advice = editorial recommendation. Uncertain / it depends = limits of what can be said in general.