How to Find Her Ring Size Without Her Knowing

You have chosen the stone, the shape and the metal. There is just one detail left — and it’s the one most likely to give the surprise away. Here is how to find her ring size quietly, and what to do if you are not completely sure.

First: how ring sizes work in South Africa

South Africa uses the same letter-based system as the UK, running from A upwards, with half sizes in between (for example K, K½, L). Each letter corresponds to the inside circumference of the ring. If you see a US number or a millimetre measurement online, it can be converted — but always confirm the letter size with your jeweller before your ring goes into production.

Six discreet ways to find her size

1. Borrow a ring she already wears

Choose a ring she wears on her ring finger (or the same finger on the other hand). Bring it to us, or measure the inside diameter carefully with a ruler. Return it before she notices.

2. Trace or press it

If you can’t take the ring away, trace the inside circle on paper with a sharp pencil, or press it gently into a bar of soap or some modelling clay. A clean impression of the inside edge is surprisingly useful.

3. Ask her best friend or sister

Someone close to her may already know her size — or can suggest “going ring shopping for fun” and casually try a few on.

4. Check her jewellery box for clues

Some rings have the size stamped inside the band.

5. The sleeping measurement

Brave, but it works: a thin strip of paper wrapped gently around the base of her finger, marked where it overlaps. Expect a margin of error.

6. Use a ring sizing kit

The most reliable method of all — especially if she already knows a proposal is coming. Our LM Jewellers Ring Sizing Kit lets you measure accurately at home, with no guessing and no unnecessary resizing.

When in doubt, size up slightly. A ring that is a touch loose is easier to adjust than one that won’t go over the knuckle.

Things that change ring size

• Temperature — fingers swell in Johannesburg summers and shrink in cold weather. Measure at room temperature.
• Time of day — fingers are often slightly larger in the evening.
• Band width — wider bands fit more snugly. For bands of around 6 mm and wider, many people go up half a size.
• Knuckles — if her knuckle is larger than the base of her finger, the ring needs to pass over it comfortably.

What if I get it wrong?

It happens, and it’s fixable. Many ring designs can be resized after the proposal. Some designs — such as full eternity bands set with stones all the way around — are much harder to resize, so for those it is worth confirming the size first. When you design your ring with us, we’ll talk you through the options for your specific design.

Need help? Book a private consultation and we’ll help you get it right.