Tennis Bracelet, Eternity Band & Riviera Stone Counts — How Many Stones You Need
Short answer: A 7-inch tennis bracelet takes about 48 stones at 3 mm, 37 at 4 mm or 30 at 5 mm. A full eternity band in a US 6 takes about 23 stones at 2 mm. A 16-inch riviera necklace takes about 73 at 5 mm. All of it comes from one line: stones ≈ (run length in mm) ÷ (stone mm + 0.4 mm) — the 0.4 mm is the metal between settings.
The formula
Every stone in a line piece occupies its own diameter plus a sliver of metal on each side. That spacing — the pitch — runs about 0.3 mm in tight shared-prong work and 0.5 mm in a heavier four-prong link. Use 0.4 mm unless you know your setter's style.
stones ≈ (finished length − clasp allowance) ÷ (stone diameter + 0.4 mm)
Clasp allowance is 10–15 mm on a bracelet, 12–18 mm on a necklace. Round down: a line that comes up one stone short is finished with a slightly longer clasp, a line one stone over cannot be finished at all.
Tennis bracelet — 7 inch (177.8 mm), 165 mm stone run
| Stone size | Approx. weight each | Stones | Approx. total weight |
|---|---|---|---|
| 2 mm | 0.03 ct | 68–69 | ≈ 2 ct |
| 2.5 mm | 0.06 ct | 56–57 | ≈ 3.4 ct |
| 3 mm | 0.10 ct | 48–49 | ≈ 5 ct |
| 3.5 mm | 0.16 ct | 42 | ≈ 6.7 ct |
| 4 mm | 0.25 ct | 37 | ≈ 9 ct |
| 4.5 mm | 0.36 ct | 33 | ≈ 12 ct |
| 5 mm | 0.50 ct | 30 | ≈ 15 ct |
For a 6.5-inch bracelet subtract about 3 stones at 3 mm, 2 at 5 mm; for 7.5 inch, add the same.
Eternity and half-eternity bands
Here the run length is the circumference the stones sit on, which is a little larger than the finger circumference because the stones ride on the outer face of the band. A workable figure is finger circumference + 3 mm.
| Ring size (US) | Stone run | 1.5 mm | 2 mm | 2.5 mm | 3 mm |
|---|---|---|---|---|---|
| 5 | ≈ 52 mm | 27 | 21 | 17 | 15 |
| 6 | ≈ 55 mm | 28 | 22 | 19 | 16 |
| 7 | ≈ 57 mm | 30 | 23 | 19 | 16 |
| 8 | ≈ 60 mm | 31 | 25 | 20 | 17 |
A half eternity is half these counts; a three-quarter is 75%. Half eternities are the safer commission — a full eternity cannot be resized, and the customer usually finds that out later.
Riviera necklaces
Same formula, longer run. At 5 mm (0.5 ct each) with a 15 mm clasp allowance:
- 16 in (406 mm) → about 73 stones
- 18 in (457 mm) → about 80 stones
- 20 in (508 mm) → about 90 stones
Graduated rivieras are counted section by section — count each size band separately and add the results. This is the one piece where ordering a single matched parcel matters most: 80 stones set side by side leave nowhere for a mismatch to hide.
Why calibration decides whether a line piece works
In a halo one oversize stone can be tucked at the back. In a line every stone is on display and adjacent to two neighbours, so a 0.1 mm difference reads as a step in the row, and a stone that sits proud catches on fabric. This is the setting type where a stated tolerance earns its money — every parcel we ship is calibrated to ±0.1 mm, sent as one lot, and filmed before dispatch.
How many to order
Add 10–15%, minimum two spares. A 48-stone bracelet is a 54-stone order. Round melee is sold by the calibrated 1-carat bag at $28 — a 5 ct tennis bracelet in 3 mm is about 5 bags plus spares — and fancy shapes are sold by the stone. No minimum order either way.
Not sure which size the piece should be? Send a photo of the design and we'll lay the stones out and photograph them for you first. How ordering by design works →
Free stone count calculator · Melee size chart: mm → carat → stones per carat · Halo stone counts · Calibration & matching guarantee · Ask Leilei on WhatsApp
Frequently asked questions
How many stones are in a 7 inch tennis bracelet?
About 48 stones at 3 mm (≈5 ct total), 42 at 3.5 mm, 37 at 4 mm, or 30 at 5 mm. The formula is stones ≈ (finished length − clasp allowance) ÷ (stone diameter + 0.4 mm); a 7-inch bracelet has roughly a 165 mm stone run after a 10–15 mm clasp allowance.
How many stones does a full eternity band take?
In a US size 6 the stone run is about 55 mm, giving roughly 28 stones at 1.5 mm, 22 at 2 mm, 19 at 2.5 mm or 16 at 3 mm. A half eternity is half those counts. Full eternity bands cannot be resized, so half eternities are often the safer commission.
How many stones are in a riviera necklace?
At 5 mm stones with a 15 mm clasp allowance: about 73 stones for 16 inches, 80 for 18 inches and 90 for 20 inches. Graduated rivieras are counted band by band and added together.
Why does calibration matter more in a tennis bracelet than a halo?
In a line piece every stone is on display and sits between two neighbours, so a 0.1 mm difference reads as a step in the row and a proud stone catches on fabric. In a halo an oversize stone can be placed at the back. Line pieces need a stated tolerance — Caratura calibrates to ±0.1 mm, ships one matched lot and films it before dispatch.