Ring Sizes Explained: How to Find Your Perfect Fit

Most people only think about ring sizing once — the moment they're proposing (or being proposed to). That's the worst possible time to realise you don't know your size. A ring that doesn't fit doesn't get worn. And a ring that doesn't get worn daily isn't doing its job.

This guide covers everything: the sizing system Heritage & Co. uses, how to measure your finger at home, and how other international sizing systems compare — so you can order with confidence and receive a ring that fits from day one.

The Sizing System We Use — US Numeric

Heritage & Co. uses the US numeric sizing system as the primary label on all products. You'll see sizes listed as whole and half numbers: 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10. Each size corresponds to a specific inner diameter and circumference — precise and repeatable.

To give you an additional reference point, we also include the UK alphabetical equivalent alongside each US size. So a size listing at Heritage & Co. looks like this: 7 / O — the US number first, UK letter second.

Full Size Chart

Most common women's sizes: 6/M – 7/O  |  Most common men's sizes: 8/Q – 10/U

A note on UK letter sizing

Our labels follow the standard US to UK conversion used by most fine jewellery houses — each US size pairs with the nearest whole UK letter. In practice, the diameter sits a touch under the UK letter shown (around 0.2mm, roughly a half-letter step). If you know your UK size precisely and prefer a more generous fit, choose the next half-size up. Or use Size TBC, and we will confirm with you over WhatsApp before production begins.

How to Measure Your Ring Size at Home

The most accurate at-home method is measuring your inner finger circumference with a flexible tape measure or a strip of paper.

Method 1 — Paper strip: Cut a thin strip of paper about 10cm long. Wrap it around the base of the finger you'll wear the ring on. Mark where the paper overlaps. Measure the length from the end to the mark in millimetres — that's your inner circumference. Match it to the table above.

Method 2 — Existing ring: If you already own a ring that fits the correct finger, measure its inner diameter in millimetres and match it to the diameter column in the chart.

Three rules that make a real difference:

• Measure in the evening — fingers swell slightly throughout the day and are largest at night.
• Measure at room temperature — cold fingers read smaller and can lead to ordering too tight.
• If you're between sizes, always go up — a slightly loose ring is far easier to size down than a tight ring is to cut off.

If you're ordering a surprise ring and don't know your partner's size, our most common women's engagement ring size is 6/M to 7/O. You can also WhatsApp us and we'll walk you through how to discreetly find out.

Why We Chose the US Numeric System

South Africa doesn't have one universal ring sizing standard. Local jewellers use a mix of US numeric, UK alphabetical, EU millimetre-based, and occasionally Swiss. This fragmentation causes more sizing errors than anything else — a "size M" from one jeweller might be a 6.25 from another.

We chose US numeric for three reasons:

1. It's the most widely understood globally. US sizing is the dominant standard in fine jewellery worldwide. Most CAD/CAM ring design software defaults to it. Every major manufacturer, stone setter, and resizer works in US numeric. When you need to have your ring resized in Johannesburg, Cape Town, or anywhere in the world, the US size is what jewellers use as the baseline reference.

2. Half sizes allow precision without complexity. The EU system uses raw circumference in millimetres — technically accurate but unfamiliar for most people. US numeric half-sizes hit the practical middle ground: granular enough to fit correctly, simple enough to order with confidence.

3. It eliminates confusion at production. When we spec a ring at 7/O, the manufacturer, the stone setter, and our QC check are all working from the same reference. No conversion. No ambiguity. The UK letter is a secondary cross-reference — the US number is the production spec.

Other Sizing Systems — How They Work

UK Alphabetical

Letters A–Z (with half sizes like J½). UK I ≈ US 4. UK O ≈ US 7. UK U ≈ US 10. Most South African high-street jewellers use UK letters when sizing in-store — which is why we include the UK letter as a secondary reference.

EU / Continental

The EU system uses the inner circumference directly as the size number. 54.4mm circumference = EU 54. Popular in France, Germany, Italy, Spain, Scandinavia. Quick conversion: US 7 / UK O = EU 54

Japanese Numeric

Japanese sizes = inner circumference in mm minus 40. 54mm = Japanese size 14 ≈ US 7. Common across East Asia. Quick conversion: US 7 / UK O = JP 14

Swiss / French-German

Swiss system = inner circumference in mm minus 40 — identical to Japanese. Swiss 14 = US 7.

International Conversion Reference

Still Unsure? We'll Help You Get It Right

If you're ordering for yourself, use the chart above and you'll be fine. If you're ordering a surprise, WhatsApp us — people have come up with some genuinely creative ways to find out a partner's ring size without giving away the proposal.

We also offer a Size TBC option at checkout — we hold production until you confirm the size via WhatsApp, then begin immediately.

Heritage & Co. Rings — Built to Your Size

Every Heritage & Co. engagement ring is made to order in your exact size. No stock rings that need resizing — yours is built to specification from the start.

Our INVICTA collection — GRA-certified moissanite (D/VVS1) in 9K gold — starts from R16,995. The AETERNA collection — moissanite in 14K gold — runs from R21,995 to R34,995. For a IGI-certified lab diamond (D/VVS1) in 18K gold, the CLARITAS collection starts at R44,995.

All rings include free custom engraving — a date, an initial, something that turns a ring into a relic.

The ring she'll reach for every day isn't just beautiful. It fits.