Common Jewellery Measurements: Sizes, Lengths and Units Explained

Jewellery uses a mix of units and conventions: centimetres and inches, ring sizes that differ by country, bangle sizes in sixteenths of an inch, stones in millimetres, wire in gauges and plating in microns. This reference brings them together in one place.

Length conversions

Centimetres	Inches
2.54 cm	1 in
15 cm	about 6 in
18 cm	about 7 in
40 cm	about 16 in
45 cm	about 18 in
50 cm	about 20 in
60 cm	about 24 in

Necklace lengths

Style	Length
Collar	30–33 cm (12–13 in)
Choker	35–40 cm (14–16 in)
Princess	43–48 cm (17–19 in)
Matinee	50–60 cm (20–24 in)
Opera	70–90 cm (28–35 in)
Rope	100 cm+ (40 in+)

See How to Choose Necklace Lengths.

Bracelet lengths

Measure your wrist, then add room for fit: about 1 cm for snug, 1.5–2 cm for comfortable, 2.5–3 cm for loose. Charm bracelets usually need a little extra. See Bracelets and Cuffs.

Bangle sizes (India)

Size	Inner diameter (approx.)
2.2	54 mm
2.4	57 mm
2.6	60 mm
2.8	64 mm
2.10	67 mm

The number after the point is sixteenths of an inch (2.6 = 2 6/16 in). See Bangles and Kada.

Ring sizes

Ring sizes vary by system (US, UK, EU, India, Japan). The most reliable approach is to measure:

Inner diameter in millimetres, or
Circumference in millimetres (diameter × π)

Then compare with the seller's chart. See Ring Size and Fit Guide.

Earring dimensions

Usually listed as length × width in millimetres or centimetres. Check whether the measurement includes the hook or post.

Stone sizes

Measurement	Meaning
Millimetres (e.g., 6 mm round)	Diameter or length × width of the stone
Carats (ct)	Weight; 1 carat = 0.2 grams (used mainly for gemstones)

For CZ and glass in fashion jewellery, millimetre size is more useful than carat weight. See Cubic Zirconia.

Bead sizes

Beads are measured by diameter in millimetres (for example 4 mm, 6 mm, 8 mm). Seed beads use a different numbering system where larger numbers mean smaller beads.

Wire gauge

Wire thickness is often given in gauge (AWG in the US) or millimetres. Higher gauge numbers mean thinner wire.

Gauge (AWG)	Approx. diameter	Typical use
18	1.0 mm	Sturdy hooks, bangles
20	0.8 mm	Ear wires, loops
22	0.64 mm	Wrapped loops
24	0.51 mm	Fine wrapping
26	0.40 mm	Delicate wrapping

See Beading and Wire Wrapping.

Plating thickness

Measured in microns (µm; one thousandth of a millimetre). For reference, US FTC guidance sets 0.175 microns of fine gold as the minimum for "gold electroplate" and about 2.5 microns for "heavy gold electroplate". See Gold-Plated Jewellery.

Weight

Jewellery weight is usually given in grams. For comfort, compare listed weights with pieces you already find comfortable. See Lightweight vs Heavy Earrings.

Metal purity (fine jewellery)

Mark	Meaning
24K	Pure gold
22K	About 91.6% gold
18K	75% gold
14K	About 58.5% gold
925	Sterling silver (92.5% silver)

HANSINI369 Bangles. Bangles in festive and everyday styles, ready to stack with the rest of your look. View Available Bangles

Key takeaway

Keep this page handy whenever you shop or make jewellery. Measuring in millimetres and comparing against each seller's own chart is the most reliable way to get sizes right.

Sources and further reading

U.S. eCFR — 16 CFR Part 23, FTC Guides for the Jewelry, Precious Metals, and Pewter Industries

Written by

HANSINI369 Editorial Team

Our editors research jewellery types, materials, care and craft, and review guides when materials, standards or recommendations change. Read our editorial policy.