Diamond chains

The Diamond Chain Calculator

Any diamond, any cut, from a 1 pointer to 100 carats, next to a real quarter.

TraxNYC Magazine

The calculator

Size your diamond chain

Drawn to scale with the quarter.

25 pointer0.25 carat each, about 4.1 mm across

Slide to size the diamond

1 pointer100 carats

The cut

The chain: length

One inch of the chain

Stones per inch: 5.7
Stones in the chain: 125
Total carat weight: about 31 carats
Chain width: about 4.5 mm

In our case near this size, with today's prices

See every tennis chain →

How the math works: a round diamond's width follows its weight, and the other cuts follow the outlines in our diamond size chart. On our own tennis chains, the stones sit about 1.1 stone-lengths apart and the chain runs about 0.4 mm wider than the stone; other cuts are counted set end to end. Every maker's setting is a little different, so each listing's own carat weight is the number you buy. Two chains with the same stones can differ a lot in price: the gold in the casting is most of the difference. The quarter is a US Mint photo; the diamonds are AI images, drawn to size.

Most diamond chains are bought off a photo and a carat number. The calculator above turns that number into something you can see: the stone next to a quarter, how many stones fit in an inch, and how many carats the whole chain carries, with the chains in our case closest to that size and their prices today. The chains under it are real pieces in our case; the diamond pictures are AI images, and the quarter is a US Mint photo.

What a pointer is

Jewelers count diamonds in points: 100 points make one carat. A 10 pointer is a tenth of a carat, a 25 pointer is a quarter carat, and a 50 pointer is half a carat. On a tennis chain, the pointer size of each stone sets everything else: how wide the chain is, how many stones fit in an inch, and the total carat weight.

Stone	Carat each	mm across	Per inch	20″ chain	22″ chain
3 pointer	0.03	2.0	11.5	6.9	7.6
5 pointer	0.05	2.4	9.7	9.7	10.7
7 pointer	0.07	2.7	8.7	12.1	13.4
10 pointer	0.10	3.0	7.7	15.4	16.9
15 pointer	0.15	3.4	6.7	20.1	22.2
20 pointer	0.20	3.8	6.1	24.4	26.8
25 pointer	0.25	4.1	5.7	28.2	31.2
30 pointer	0.30	4.3	5.3	32.1	35.1
50 pointer	0.50	5.1	4.5	45.0	49.5
75 pointer	0.75	5.9	3.9	59.2	64.5
1 carat	1.00	6.5	3.6	71	79

The 20″ and 22″ columns are total carats in the whole chain. The table is for one row of round diamonds in four prongs, the way our tennis chains are set. We checked it against our own chains: by the table, a 20 pointer chain at 22 inches carries about 27 carats, and two of our chains at that size carry 26.0 and 26.3. Each listing states its own carat weight, and that is the number you buy.

Natural diamond chains, made the right way

“Diamond chains are one of the most expensive pieces of jewelry somebody can own. For 20 years I've been making natural diamond chains, and only four or five customers have ever had one made the way it's supposed to be made: big stones, all real VS. You're talking about 25 pointers, a quarter carat each stone, on the right casting. Or even bigger, half carats. The people that do one carats go GIA certified, and those chains can be in the hundreds of thousands of dollars.”Trax, at the jewelry store on 47th Street since 2004

Run those sizes through the calculator. A 22-inch chain of 25 pointers is about 125 stones and 31 carats; of half carats, about 99 stones and 50 carats; of one carats, about 79 stones and 79 carats. Every natural stone in a chain like that has to match the others in color and clarity, and the matching is where the price goes.

Lab-grown: the shine without the million dollars

“Now with lab, you can have VVS, pay mostly for the gold, and have the most shining chain ever. It's an incredible time for diamond chain fans that don't have a million dollars to drop. For a reasonable price you can wear two diamond chains, which is the real look. Because when you have one diamond chain, you realize one is not enough.”Trax, at the jewelry store on 47th Street since 2004

AI image: two diamond tennis chains in yellow gold worn together, one with smaller stones and one with bigger stones — Two chains, the real look. AI image.

A lab-grown diamond is a real diamond: the same carbon crystal, as hard and as bright as a mined one, grown above ground instead of dug up. VVS means very, very slightly included, with flaws you can't find without strong magnification. That is Trax's point: with lab-grown stones, VVS at chain sizes is within reach, and much of what you pay for is the gold. For the full comparison, read lab-grown or natural and what VVS means.

How Trax checks a diamond chain

“If someone brought me a VVS diamond chain, I would test it with my tester. And if it was far below the price I could make it for myself, I'd buy it, if the casting was the quality I like and it was in good condition.”Trax, at the jewelry store on 47th Street since 2004

Three checks are in that answer.

The tester. A diamond tester tells a diamond from a fake. A basic heat tester can pass moissanite as a diamond; a tester that also reads electrical current catches it. A standard tester can't tell lab-grown from natural, because both are diamond: that takes lab equipment, and the proof is a report from GIA or IGI.
The casting. Under a loupe, every stone sits level, every prong holds its stone, the links bend freely, and the clasp closes with a safety.
The price against the stones. Count the stones and the carats with the calculator above. A chain priced far below what its carats and gold should cost tells you to test it before anything else.

More you can check at home: how to tell if a diamond is real, and the setting, prongs and clasp in our diamond tennis chain guide.