A US ring size is a number that corresponds to the inside measurement of the band: size 6 is about 16.5 mm across the inside, size 7 about 17.3 mm, and each half size adds roughly 0.4 mm of diameter. To find your size at home, either measure the inside diameter of a ring you already wear or wrap a strip of paper around the finger and measure its length, then read the number from a standard conversion table. Two things decide the final answer: the knuckle the ring has to pass, and the season, because fingers change size. This guide covers both, adds the notes that matter for a bezel-set cabochon on a silver band, and ends with what to ask us before you order.
How US ring sizes work
The US system covers most adult hands between about size 3 and size 13, in half-size steps, and each number corresponds to a fixed inside circumference. Size 3 measures about 44.2 mm around the inside. Every full size adds roughly 2.55 mm of circumference, which works out to about 0.8 mm of diameter, so a half size is roughly 1.3 mm of circumference: small enough that many people cannot feel it, and large enough to be the difference between a ring that turns and one that will not come off.
The British and Australian systems use letters, and European sizes are usually the inside circumference in millimeters, so a European 54 corresponds to a US 7. If you already have a size from another system, convert it through the circumference rather than through a rounded chart, and confirm it against your own measurement.
Two ways to measure at home
Measure a ring that already fits
This is the more reliable of the two methods. Take a ring you wear comfortably on the intended finger, lay it flat on a ruler, and measure from inside edge to inside edge across the widest point. That number is the inside diameter in millimeters. Read it against the table below and round to the nearest half size. Measure twice, and use a plain band if you have one, since a wide or heavily domed band sits differently on the finger.
Measure the finger with a paper strip
Cut a strip of paper about 5 mm wide, wrap it snugly around the base of the finger, mark where it overlaps, then lay it flat and measure to the mark in millimeters. That length is the inside circumference. Check that the strip passes over the knuckle before you take the reading. Use paper rather than string, which stretches, and do not pull it tight.
Two cautions apply to both methods. A printable paper ring sizer is only accurate if the page prints at exactly 100 percent, so check it against the scale bar the sheet prints alongside. And a plastic ring sizer or a jeweler’s steel mandrel will beat either method at home; if a local jeweler will size you in person, that is worth the trip.
Knuckles, seasons and the time of day
Finger size is not a constant. Most people run about half a size larger at the end of a warm day than first thing on a cold morning, and heat, salt, exercise, air travel and hormonal cycles all move the number. A ring that fits perfectly in July can spin in January.
The knuckle is the harder problem. If your knuckle is noticeably wider than the base of the finger, the ring has to be sized to pass the knuckle, which leaves it looser below. The usual compromise is to size for the knuckle and accept some movement, and on a plain band a local jeweler can later fit sizing beads or a small internal bar. Measure at the end of the day, at room temperature, and take the larger reading when you fall between two sizes.
If a ring is a gift and you cannot ask, the most common women’s sizes fall between US 5 and 7 and the most common men’s sizes between US 9 and 11. Those are starting points for a guess, not a substitute for measuring.
US size to inside diameter: standard reference table
The table below is the standard conversion used across the jewelry trade. It is a general reference for moving between size, diameter and circumference. It is not a measurement of any particular piece in our catalog.
| US size | Inside diameter (mm) | Inside circumference (mm) |
|---|---|---|
| 4 | 14.9 | 46.8 |
| 4.5 | 15.3 | 48.0 |
| 5 | 15.7 | 49.3 |
| 5.5 | 16.1 | 50.6 |
| 6 | 16.5 | 51.9 |
| 6.5 | 16.9 | 53.1 |
| 7 | 17.3 | 54.4 |
| 7.5 | 17.7 | 55.7 |
| 8 | 18.1 | 57.0 |
| 8.5 | 18.5 | 58.3 |
| 9 | 18.9 | 59.5 |
| 9.5 | 19.4 | 60.8 |
| 10 | 19.8 | 62.1 |
| 10.5 | 20.2 | 63.4 |
| 11 | 20.6 | 64.6 |
| 11.5 | 21.0 | 65.9 |
| 12 | 21.4 | 67.2 |
If your measurement falls between two rows, take the larger size, particularly for a ring with a wide band or a set stone.
Wearing a bezel-set cabochon ring on a silver band
A bezel-set cabochon behaves differently from a plain band. The points below are general to this style of ring, wherever it was made.
- Sizing is limited. As a general matter, a bezel-set stone ring is harder to resize than a plain band. The bezel and the shoulders are part of the structure holding the stone, and heat and pressure near a set stone carry risk. Many jewelers decline this kind of work, and those who accept it will often move a ring only a fraction of a size. Treat the size you order as the size you intend to wear.
- The dome adds height. A cabochon sits above the finger, so it catches on gloves, pockets and bag straps more than a flat band does. Rings with a raised stone are usually best taken off before sports, heavy lifting, gardening and cleaning.
- Weight shifts the balance. A stone set on top makes a ring top-heavy, so a band that is slightly loose will rotate and sit off center. That is a fit signal worth acting on rather than living with.
- Silver is a softer metal. S925 silver is an alloy of 92.5 percent silver, softer than gold or platinum. It marks and bends more easily, and it darkens over time with air, humidity, perfume and household chemicals. A soft cloth and dry storage do most of the work; the jade care notes cover the rest.
- Jadeite is tough, not indestructible. Its interlocking structure makes it resistant to chipping compared with many gemstones, but a hard knock against stone, tile or a countertop edge can still damage a cabochon or its setting.
Before you order
Every piece here is one of one, so a ring is not a size that can be re-picked from a shelf. Two habits make that work in your favor.
- Measure first, then look. Knowing your size before you fall for a stone saves the disappointment of a piece that does not fit.
- Ask about the specific piece. If the size of a particular ring would change your decision, write to us and ask for its current measurement before ordering. We would rather answer a question in advance than have a piece arrive that cannot be worn.
Orders are Final Sale. There is an exception path within seven calendar days of delivery for a mis-ship, transit damage, or a piece that is materially not as described; fit is something to settle before ordering, not after. That is the whole reason to ask first.
How JADE ALL DAY applies this
We work from our own bench in Stillwater, Minnesota. Each ring is photographed and filmed there, with four or five studio photographs and a video of that exact piece, and is held in single stock, one of one, not restocked once it sells.
Each stone is set in S925 silver. The vocabulary we use for translucency and color is explained in the translucency and color guide, and what we do and do not claim about the material is set out in natural jadeite vs treated jadeite. We publish the facts we have verified and leave out the ones we have not.
We ship to the United States and Canada, standard delivery takes seven to fourteen business days, and standard shipping is free from 49 USD or CAD after discounts. Browse the rings, or look at earrings, bracelets and bangles and necklaces if a piece without a size suits you better. Everything available is in the shop, and we are glad to give you a measurement before you decide.