Size & conversion charts
The tables product teams reach for when writing a specification. Sizes are stated to industry standard; we hold whatever you specify across the run.
Ring size conversion
| US | UK | EU | Inside diameter (mm) | Circumference (mm) |
|---|---|---|---|---|
| 4 | H | 47 | 14.9 | 46.8 |
| 5 | J½ | 49 | 15.7 | 49.3 |
| 6 | L½ | 52 | 16.5 | 51.9 |
| 7 | N½ | 54 | 17.3 | 54.4 |
| 8 | P½ | 57 | 18.1 | 57.0 |
| 9 | R½ | 59 | 19.0 | 59.5 |
| 10 | T½ | 62 | 19.8 | 62.1 |
| 11 | V½ | 64 | 20.6 | 64.6 |
| 12 | Y | 67 | 21.4 | 67.2 |
| 13 | Z+1 | 69 | 22.2 | 69.7 |
Round brilliant — carat to millimetre
| Carat | Diameter (mm) |
|---|---|
| 0.10 ct | 3.0 mm |
| 0.25 ct | 4.1 mm |
| 0.50 ct | 5.2 mm |
| 0.75 ct | 5.8 mm |
| 1.00 ct | 6.5 mm |
| 1.50 ct | 7.4 mm |
| 2.00 ct | 8.2 mm |
| 3.00 ct | 9.4 mm |
| 4.00 ct | 10.4 mm |
| 5.00 ct | 11.2 mm |
Necklace & bracelet lengths
| Type | Length | Sits at |
|---|---|---|
| Choker | 14–16 in / 36–41 cm | Base of the neck |
| Princess | 17–19 in / 43–48 cm | Collarbone |
| Matinee | 20–24 in / 51–61 cm | Top of the bust |
| Opera | 28–36 in / 71–91 cm | Below the bust |
| Bracelet — S | 6.5 in / 16.5 cm | Snug fit |
| Bracelet — M | 7 in / 17.8 cm | Standard womens |
| Bracelet — L | 7.5 in / 19 cm | Loose fit |
| Bracelet — Mens | 8–9 in / 20–23 cm | Standard mens |
What a size run actually decides
Ring sizes are not universal
US, UK and EU systems measure differently, and a customer who knows their size in one system does not know it in another. If you sell across markets, state which system your specification uses — we have shipped identical runs labelled two ways because a spec said "size 7" without saying whose 7.
Full eternity bands cannot be resized
Stones set around the entire circumference leave nowhere to cut. That makes the size distribution a commercial decision at order stage rather than a service question later. Partial-set anniversary bands with a plain sizing bar keep that flexibility.
Carat is weight, millimetre is what the customer sees
Two stones of equal carat can look different sizes depending on cut proportions. Elongated shapes — oval, marquise, emerald — read larger than their weight. When your specification targets a look rather than a weight, give us the millimetre spread and we will source to it.
Chain length sells the piece
A pendant at 16 inches and the same pendant at 20 inches are different products to the customer. Where you are pairing pendants with chains, specify length by market: US retail moves 18 inches, several European markets sit shorter.
Need a size run built into your programme?
Tell us the size distribution your market needs and we build it into the production plan.
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