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Most tennis necklaces are 16 or 18 inches long. A 16 inch necklace sits at the base of the neck, an 18 inch necklace just below the collarbone and a 20 inch necklace at the top of the neckline. On an 18 inch necklace set with round lab grown diamonds all the way round, 2 mm stones give about 190 diamonds and 5.5 carats, 2.6 mm stones about 10 carats, and 3 mm stones about 134 diamonds and 13 carats.
Below, length, stone size, stone count and total carat weight are worked out the same way as on our tennis bracelet size guide, followed by layering, clasp care, how to choose by neckline and the two tennis necklaces we make.
| Length | Where it sits | Good for |
|---|---|---|
| 16 in | At the base of the neck | The classic close tennis look, open collars, strapless and off the shoulder necklines |
| 17 in | Between the base of the neck and the collarbone | A little more room than 16 in; our 10 carat necklace is listed at this length |
| 18 in | Just below the collarbone | Most necklines, and the easiest first length |
| 20 in | At the top of the neckline | V necks, layering under a shorter necklace, and many men |
These positions assume an average neck. To check your own, measure around the base of your neck with a soft tape and add about 2 inches. That is the shortest length that lies flat instead of pressing on the throat. On a larger neck every length sits a little higher, so go up one length. If you are buying a gift, lay a necklace she already wears flat and measure it from end to end, clasp included.
Two numbers decide a tennis necklace: the size of each stone and how many of them fit along the length. Stone size is quoted in millimeters, and the total carat weight follows from it. The weight of a round diamond grows with the cube of its width, so a 4 mm stone weighs about 8 times as much as a 2 mm stone while looking only twice as wide.
| Stone size | 16 in necklace | 18 in necklace | 20 in necklace |
|---|---|---|---|
| 1.5 mm (0.012 ct each) | 213 stones, 2.62 ct | 240 stones, 2.95 ct | 267 stones, 3.28 ct |
| 2.0 mm (0.029 ct each) | 169 stones, 4.92 ct | 190 stones, 5.53 ct | 211 stones, 6.15 ct |
| 2.5 mm (0.057 ct each) | 140 stones, 7.97 ct | 157 stones, 8.93 ct | 175 stones, 9.96 ct |
| 3.0 mm (0.098 ct each) | 119 stones, 11.70 ct | 134 stones, 13.17 ct | 149 stones, 14.65 ct |
| 3.5 mm (0.156 ct each) | 104 stones, 16.24 ct | 117 stones, 18.27 ct | 130 stones, 20.30 ct |
| 4.0 mm (0.233 ct each) | 92 stones, 21.44 ct | 103 stones, 24.00 ct | 115 stones, 26.80 ct |
| 5.0 mm (0.455 ct each) | 75 stones, 34.14 ct | 84 stones, 38.23 ct | 94 stones, 42.79 ct |
These figures are approximate. We count the same way as on our bracelet guide: about 0.4 mm of metal between stones, counts rounded down to whole stones, and the total is the count multiplied by the weight of one stone. Real necklaces usually hold fewer stones than the table, because the clasp takes up space, many designs finish with plain metal links near the clasp, and some set diamonds across the front only. Ask us for the exact stone count, stone size and total carat weight for the length you want before you order. If you are comparing lab diamond tennis necklaces between shops, ask each one for the stone size in millimeters, since the carat total alone does not tell you how wide the line will look.
| Target total | 16 in necklace | 18 in necklace |
|---|---|---|
| 3 ct | 1.6 mm, about 203 stones | 1.5 mm, about 240 stones |
| 5 ct | 2.0 mm, about 169 stones | 1.9 mm, about 198 stones |
| 7 ct | 2.4 mm, about 145 stones | 2.2 mm, about 175 stones |
| 10 ct | 2.8 mm, about 127 stones | 2.6 mm, about 152 stones |
| 15 ct | 3.4 mm, about 106 stones | 3.2 mm, about 127 stones |
| 20 ct | 3.9 mm, about 94 stones | 3.7 mm, about 111 stones |
A tennis necklace needs far more carats than a tennis bracelet for the same look, because it is more than twice as long. Stones of 3 mm add up to about 5 carats on a 7 inch bracelet and about 13 carats on an 18 inch necklace.
From a normal distance the diamonds read as one line, so stone size reads as the width of that line.
Shown: 10 carat tennis necklace, from $3,080 in 925 silver.
A uniform necklace keeps every stone the same size, for an even band of light all the way round. A graduated necklace puts the largest stones at the centre and steps down toward the back, so the front shows bigger stones than a uniform necklace of the same total weight, and the sides stay light.
Every link of a tennis necklace hinges, so any tennis necklace can turn over now and then and show the back of its settings. It happens most with a light, uniform line on a length that hangs loose. Two things help: a length that rests at the base of the neck or on the collarbone rather than swinging, and a design that carries more weight at the front, as a graduated necklace does.
In a layered look the tennis necklace is usually the shortest piece. Leave about 2 inches between layers so each one has its own space: a 16 inch tennis necklace, an 18 inch pendant and a 20 inch chain is a simple stack. If your tennis necklace is 18 inches, move the pendant to 20 inches.
Keep one piece as the focus. Next to a bold tennis line a small solitaire pendant looks better than a large one, and the other way round. Our pendant size guide shows how big each carat weight looks on the neck, and our lab grown diamond pendants come in the same gold colors as our tennis necklaces, so a stack can match.
Both of our tennis necklaces close with a lobster clasp. On our 10 carat necklace the last links before the clasp are plain polished metal, and the clasp sits on a short round link chain.
Every Ronora piece has a lifetime warranty on manufacturing defects, which we repair free of charge. Wear and knocks are paid repairs, and we always quote first.
| Neckline | Length | Why |
|---|---|---|
| Crew or high round neck | 16 in | The line sits just above the fabric instead of disappearing under it |
| V neck | 18 in, or 20 in for a deep V | The necklace follows the opening and fills the top of the V |
| Scoop neck | 18 in | It rests on bare skin between the collarbones and the neckline |
| Open collar shirt | 16 or 18 in | It frames the opening; 18 in shows more of the line |
| Strapless, off the shoulder or sweetheart | 16 in | It frames the neck and collarbones with nothing competing |
| Turtleneck or high knit | 18 or 20 in, over the fabric | It rests on the knit instead of pressing at the throat |
If you wear many different necklines, 18 inches is the safest single choice.
Shown: 10 carat tennis necklace, from $3,080 in 925 silver.
We make two tennis necklaces in our own workshop in Surat, India. Both use round lab grown diamonds, Excellent cut, D-E-F colorless with VVS-VS clarity, set by hand in 9K, 14K or 18K solid gold (white, yellow or rose), platinum or 925 sterling silver.
| Metal | Round tennis necklace, 5 ct graduated | 10 carat tennis necklace |
|---|---|---|
| 925 sterling silver | $1,880 | $3,080 |
| 9K gold | $2,630 | $5,900 |
| 14K gold | $3,270 | $7,690 |
| 18K gold | $4,100 | $10,480 |
| Platinum | $3,750 | $9,960 |
Prices are regular prices, checked on 26 October 2026. Each necklace is made to order: we make your piece in 10 days and deliver it in 10 to 15 days, with free insured standard shipping. Every gold piece comes with an SGL jewelry certificate and every platinum piece with an ITPL certificate. See both in our lab grown diamond tennis necklace collection, or send us the length and carat weight you have in mind.
10 carat tennis necklaceFrom $3,080 in 925 silver
Round tennis necklace, 5 ct graduatedFrom $1,880 in 925 silver
Three stone pendant, to layerFrom $910 in 925 silver
Regular prices, checked on 27 October 2026.
Questions? WhatsApp us about size, metal or price for any piece in this guide.
Most people choose 16 or 18 inches. A 16 inch tennis necklace sits at the base of the neck and an 18 inch necklace just below the collarbone, which suits most necklines. Measure around the base of your neck and add about 2 inches for the shortest length that lies flat.
It depends on the stone size and the length. With round diamonds all the way round an 18 inch necklace, 2 mm stones give about 190 diamonds, 3 mm stones about 134 and 4 mm stones about 103. Necklaces with plain links near the clasp, or with diamonds across the front only, hold fewer.
On an 18 inch necklace, 3 to 5 carats gives a fine everyday line of 1.5 to 2 mm stones. Around 7 to 10 carats, with stones of about 2.2 to 2.6 mm, reads clearly as diamonds, and 15 carats and above, with stones of 3.2 mm and up, is a statement piece.
Any tennis necklace can turn over now and then, because every link hinges. It happens less when the necklace rests snugly at 16 or 18 inches instead of swinging loose, and when the design carries more weight at the front, as a graduated necklace does.
Yes. A fine line of 1.5 to 2.5 mm stones is made for daily wear. Take it off for sleeping, swimming and the gym, check that the clasp is closed each time, and have the prongs looked at if a stone ever seems loose.
Yes. Men often choose 20 inches or a little longer. Our 10 carat tennis necklace is worn by women and men, and we make other lengths on request.
