Choosing Side Stones for a Centre Stone — Sizes, Shapes and Counts

Short answer: Side stones read right when each one is about a quarter to a third of the centre stone's weight and its width is 55–70% of the centre's width. Most three-stone and shoulder settings take 2 to 8 stones. Which shape you use is decided by the centre stone's outline: step cuts pair with baguettes and trapezoids, brilliant cuts with pears, ovals and half-moons.

Sizing: two rules that agree with each other

By weight — each side stone at 25–33% of the centre. A 2 ct centre takes side stones of roughly 0.5–0.65 ct each.

By width — the side stone's width at 55–70% of the centre's width, so the shoulder steps down visibly without the ring looking broken. An 8 mm centre takes sides about 4.5–5.5 mm wide.

The two rules land in the same place for most stones. When they disagree — usually with long shapes like marquise or emerald — trust the width. A ring is judged from above, not on a scale.

Which side-stone shape goes with which centre

A worked example: a 14 × 7.5 mm emerald cut centre sits well with trapezoid or straight baguette sides in the 2 × 3 mm to 2 × 4 mm range — small enough to keep the centre dominant, straight enough to sit flush against it. Add 2 mm rounds on the outer shoulders only if the shank is long enough; on a compact setting there is no room, and forcing them is the most common reason a three-stone design has to be redrawn.

Typical counts

• Classic three-stone — 2 stones.
• Three-stone with a step down — 4 stones (two sizes, mirrored).
• Tapered shoulders — 4 to 8 stones, usually stepping down 0.5 mm at a time.
• Side stones plus a pavé shank — 2 side stones plus 12–24 melee at 1.0–1.5 mm.

Order the mirrored pairs together. Side stones are the one place where two stones from different batches are noticed immediately, because they sit symmetrically two centimetres apart on the same hand.

The mistake that costs a redraw

Most side-stone designs fail on height, not width. A side stone with a deeper pavilion than the centre sits higher in its seat, and the three crowns no longer read as one plane. If you are matching to an existing centre stone, tell us its depth as well as its outline — or send a photo of the centre stone next to a ruler and we'll match to it.

How to get this decided in one message

Send the centre stone's mm dimensions and a picture of the setting you're building. We put the actual candidate side stones against your centre stone, photograph and film them, and send you the layout — rotated, swapped for a different shape, whatever it takes — before you pay. Sizes we don't stock can be cut to order. How ordering by design works →

Shapes we cut and calibrate to ±0.1 mm: baguette, trapezoid, pear, trillion, emerald, oval, marquise, princess, radiant, cushion, asscher, heart, triangle.

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Frequently asked questions