Why ring size deserves care
A ring that fits well feels secure without pinching, slides over the knuckle with a little resistance and does not spin around constantly. Getting it right matters more for an engagement ring than for most jewellery, because it is worn every day and some designs cannot be resized easily.
This guide explains the most reliable ways to find a size, how to estimate one discreetly for a surprise, and how resizing works with us. For a printable chart, see our ring size guide page.
The most accurate way: professional sizing
A jeweller's ring sizers, a set of metal rings in graded sizes, give the most reliable result. If possible:
- Measure at the end of the day when fingers are at their typical largest.
- Measure at a comfortable temperature. Cold shrinks fingers and heat swells them.
- Try wide and narrow sizers. A wide band feels tighter than a narrow one of the same size, so match the sizer width to your intended band.
- Check the knuckle. The ring must pass over the knuckle, which may be larger than the base of the finger.
Measuring an existing ring
If the wearer already has a ring that fits the intended finger, it is one of the best references:
- Measure the inside diameter across the centre with a ruler or calipers, in millimetres.
- Compare it with a size chart, such as the one on our ring size guide.
- Make sure the ring is worn on the same finger and hand. Dominant hands are often slightly larger.
A ring worn on a different finger can still help, but expect a difference. Ring fingers and middle fingers are rarely the same size.
Measuring with string or paper
This method is convenient but less precise:
- Wrap a thin strip of paper or non-stretch string around the base of the finger.
- Mark where it overlaps, keeping it snug but not tight.
- Measure the length in millimetres. That is the circumference.
- Check that it can pass over the knuckle.
- Compare it with a circumference chart.
Paper and string can stretch or be pulled too tightly, so treat the result as a starting point, not a final answer.
Discreet methods for a surprise
Many proposals are planned in secret. Some options:
- Borrow a ring they already wear on that finger, briefly, and measure the inside diameter, or trace the inside circle on paper.
- Ask a trusted friend or family member to find out casually.
- Compare with your own fingers. If their ring fits on one of your fingers, have that finger sized as a reference point.
- Estimate thoughtfully. If you must guess, a slightly larger size is generally easier to manage than one too small.
Different sizing systems
Countries use different systems. US and Canadian sizes are numbers, UK and Australian sizes are letters, and many other countries use circumference in millimetres. Hong Kong uses its own numbered system. Always confirm which system a size refers to before ordering. When in doubt, give us the measurement in millimetres.
How band width and design affect fit
- Wide bands (roughly 4 mm and above) feel tighter, and you may need a slightly larger size.
- Comfort-fit bands, rounded on the inside, can feel looser than flat-inside bands.
- Full pavé or eternity designs have stones all the way round and are difficult or impossible to resize, so accuracy matters even more.
Resizing with STELLIVON
We build your CAD model around the ring size you give us, so it is worth confirming the size before you approve the CAD. After delivery, one size change is free (you cover shipping), where the design allows it. A change of up to 2 Hong Kong sizes is possible but requires a new band, charged separately; your centre diamond is reused. Designs with stones around the whole band may not be resizable, and we will tell you at the CAD stage if this applies.
As with every STELLIVON ring, a 75% deposit begins the commission, and the balance is due after CAD approval. The deposit is refundable if you cancel before production. Because each ring is made for one person, we do not accept returns after production. The full details are in our Custom Order Terms.
Sizing for different design types
- Solitaire on a plain band: resizing is usually simple, so an estimated size is less risky.
- Half-pavé: the plain underside allows some adjustment.
- Full pavé or eternity: stones all round the band make resizing difficult or impossible, so measure carefully.
- Tension or unusual shanks: these may not be resizable. We will tell you at the CAD stage.
Seasonal and daily changes
Fingers can vary by up to a size between a cold winter morning and a hot summer afternoon. If the wearer's fingers vary a lot, choose a size that is comfortable most of the time and slips over the knuckle on a cold day. Comfort-fit interiors can help a ring slide on and off more easily.
Engagement ring and wedding band together
If the two rings will be worn together on one finger, the combined width makes the stack feel tighter. Some people size the pair slightly larger than a single ring. Discuss this with us if you plan to design both.
A quick sizing checklist
- Measured at the end of the day
- Measured at a comfortable temperature
- Knuckle checked
- Band width considered
- Sizing system confirmed, or the size given in millimetres
- Size confirmed before CAD approval
Understanding size conversions
Size systems are not perfectly aligned. Half sizes and quarter sizes exist in some systems but not others, so converting between countries can introduce small errors. The most reliable way to share a size internationally is the inside diameter or circumference in millimetres, measured from a ring that fits well. When you send us a size, tell us the system and, if you can, the measurement in millimetres too.
Signs a ring does not fit
- Too tight: it leaves a deep mark, is hard to remove, or the finger feels swollen.
- Too loose: it spins constantly, slides past the knuckle easily, or the stone falls to one side.
- Mixed: it is tight over the knuckle but loose at the base. That is a common pattern, and sizing beads or a shaped shank can help.
Measuring both hands
Even if the ring is meant for the left hand, measure both. Some people later prefer to wear the ring on the other hand, for example for work or during pregnancy, and knowing both sizes helps with planning. If the two hands differ by more than the resize allowance, mention it at the brief.
When to measure
Fingers change through the day. Measure in the evening at a normal room temperature, not straight after exercise or a hot shower, and not on a cold morning. Measure three times on different days and use the most consistent result.
Frequently asked questions
Do fingers change size? Yes, with temperature, time of day, pregnancy, weight changes and age. Measure at a typical moment.
Should an engagement ring be tight? It should be snug enough not to slide off, but it should pass over the knuckle without force.
What if their knuckles are much larger than the base of the finger? Ask us about sizing beads or a slightly shaped shank. These can keep a ring from spinning while still passing over the knuckle.
Can I order without knowing the size? Yes. We can work with an estimate. Just confirm the size before you approve the CAD, because the ring is modelled to that measurement.
Is resizing included? One size change is free (you cover shipping). A change of up to 2 Hong Kong sizes is possible but requires a new band, charged separately; your centre diamond is reused. Ask us about the details for your design.
Before you start
Find the size using one of the methods above, then start with a setting or start with a diamond.