The play, in two minutes
Borrow a ring she already wears on her left ring finger, take it to a jeweller, have it measured, put it back the same day. That is the whole method, and it beats every clever alternative on the internet. If you cannot get hold of a ring, recruit one person close to her. If you cannot do that either, order AU N½, which is US 7, and plan on a resize.What makes this hard is not the measuring. It is that the accurate methods and the invisible methods are mostly different methods. Worth knowing before you start: the corner you want has three things in it.
Seven ways to get the number, plotted against both things you care aboutAsking her sits at the right-hand edge because it is the only method that cannot be wrong. It is high on the chart because she will know you asked, which is not the same as knowing when, where, or what the ring looks like. Plenty of couples choose the ring together and the proposal still lands as a surprise.
Note what is in the bottom right. A borrowed ring, a sizer posted to a friend, and a quiet word with her sister all get you close enough to cut metal, and none of them require her to notice anything. The tricks that feel most like espionage, the string round a sleeping hand in particular, are the ones that are both risky and wrong.She noticesShe never knowsExact to the letter
Across: how close the answer gets you · Up: how likely she is to work out whyTake a ring she wears to a jeweller
Post a sizer set to her best friend
Ask her sister or her mum
Ask her outright
String round a sleeping finger
Try her ring on your own finger
Guess from a photo of her hand
Borrow a ring she already wears
This is the method, so it is worth doing properly. Four moves, and the failure in each one is a timing problem rather than a technical one.
The borrow, in four movesPick the right ringLeft hand, fourth finger, something she wears most days so the band has settled to that finger.Borrow it brieflyOvernight, or a morning she is out and the ring is in the dish. You need it for as long as the drive to a jeweller.Have it measured properlyAny jeweller will slide it down a steel mandrel and read the size off in seconds, and will not charge you for it.Put it back as it wasSame dish, same drawer, same angle it was lying at.If she keeps her rings on, the window is while she showers or swims. Ten minutes is enough to photograph where it was sitting, take it, and be back before she is dry, so long as the jeweller is a separate trip.
Bring the ring itself. Not a photo of it, not a tracing, not a note of what it says stamped inside, because the stamp is often the size the ring started life as rather than the size it was last altered to. A jeweller reading the actual band takes about four seconds and will not ask you why.1
Where it goes wrongA ring off her right hand reads about half a letter large. Her middle finger reads a full size large.
2
Where it goes wrongTaking it on Friday and returning it Sunday. Absence is what gets noticed, not the measuring.
3
Where it goes wrongTracing it on paper at home. A tenth of a millimetre of pencil is a quarter of a size.
4
Where it goes wrongCleaning it first. A ring that comes home suspiciously bright is the tell that ends the surprise.
If she only wears rings on her right handTake the measurement anyway and tell whoever is making the ring that it came from the right hand. The dominant hand usually runs a little larger, so we would come down about half a letter, and we would rather do that arithmetic ourselves than have you do it and not mention it.
One accomplice, three messages
If there is no ring to borrow, the next best thing is a person. One person, chosen for discretion rather than closeness, and told plainly that it is a secret. The wording matters more than the choice, because a question that sounds like a proposal gets forwarded to a group chat before you have put your phone down.
Three messages you can send as they are writtenWhoever you pick, give them a job with an end: a size, by a date, and no mention of it afterwards. Vague conspiracies leak. A specific errand does not.
A sizer set is the accomplice's best tool. They cost a few dollars, they post in a padded envelope, and they turn a guess into a measurement. Have it sent to your accomplice rather than to your house, then have her try them on during something ordinary. Ask for the size she can get on and off comfortably, not the one that goes on easiest.To her sister or best friend
“I am going to propose. I need her ring size and I need her not to know I asked. Can you get it?”
People who are handed a secret keep it. People who work one out tell someone within a day, usually to check whether they are right.To her mum
“Do you happen to know what ring size she takes? I am having something made and I want to get it right.”
It is true, and it is calm. If it does get repeated, it repeats as jewellery rather than as a proposal.To her, if you would rather be certain
“I want to buy you a ring one day. What size are you?”
The date, the place and the ring itself are all still yours. The only thing you have given away is a letter of the alphabet.The tricks that miss, and by how much
Most covert sizing advice online is a variation on wrapping something round a finger, or holding something up to a screen. They are not all equally bad, but they are all worse than they sound, and it helps to see how much worse. Australian sizes step in letters of 0.4 mm, so this is what each method costs in letters.
How far each method lands from the truth, drawn to one scaleGold band: close enough that the ring still fitsErrors are typical, not worst case. The wrapped methods are converted from circumference to diameter before being read as a size, which is exactly the step most string-and-ruler instructions on the internet leave out.
String and paper strips read small, because string stretches under tension and paper bites into the skin. They also cannot pass a knuckle, which is the measurement that decides whether a ring goes on at all. Doing it to a sleeping hand adds the risk of waking her while tying cotton round her finger at 2am, which takes some explaining.The printable chart is a good idea ruined by screens. Print it, and print it at one hundred percent scale rather than fit-to-page, or the whole thing is out by however much your printer decided to shrink it. Laying a ring on the chart on a monitor is not a measurement of anything.And no, you cannot read a size off a photograph. There is nothing in the frame to scale against, hands change size through the day, and the camera flattens the knuckle that half of the fit depends on.Jeweller measures a borrowed ring± 0.3 letters
Plastic sizer she actually wears± 0.5 letters
Steel rule across a borrowed ring± 0.9 letters
String or floss round the finger± 2 letters
Paper strip round the finger± 2.5 letters
Ring laid on a chart on a screen± 2.5 letters
Compared against your own finger± 3 letters
Read off a photograph± 4 letters
If you never find out, order this
Sometimes there is no ring, no accomplice and no time. Then you are guessing, and the sensible guess is the middle of the range: AU N½, which is US 7, 17.3 mm across the inside. Roughly the same guess that the whole industry makes when it decides which sizes to keep in stock.People ask what those numbers look like, usually meaning: is a size 6 tiny, is a size 8 big? Here they are drawn as the bands themselves, to one scale.
US 6, 7 and 8 as the bands themselves, drawn to one scaleSmallest to largest is 1.6 mm, or 4 Australian letters. Every ordinary women's ring size in the country lives inside that gap, which is the reason a confident guess is usually a size out.Diameters are inside measurements from the chart our workshop cuts to. AU letters are shown alongside because an Australian jeweller will ask for the letter, and the half sizes L½, N½ and P½ are the ones the US numbers land on.
A US size 6 is 16.5 mm across, an AU L½, and there is nothing small about it in any sense that matters. A size 8 is 18.1 mm, an AU P½, and it is not a big hand: ring size tracks knuckle width and bone, and has no relationship to height, dress size or anything else people quietly worry it says about them. The three of them together span 1.6 mm. That is the entire argument.US 6 · AU L 1/216.5 mm across, 51.9 mm aroundBelow the middle of the range, and ordinary. Common on fine-boned hands.
US 7 · AU N 1/217.3 mm across, 54.4 mm aroundThe busiest size in the country. Order this one if you are guessing blind.
US 8 · AU P 1/218.1 mm across, 57.0 mm aroundAbove the middle, and no more remarkable than a shoe size. Ring size follows knuckle width, nothing else.
Guessing? Be wrong slightly largeOnce you know her size, the rule is to be wrong small, because a ring that is loose spins and gets lost while a tight one can be opened up. A blind guess for a proposal is the exception. The ring has to go onto her finger in the moment, so half a letter large is the forgiving direction, and coming back down is the easier alteration anyway.
Rings that can move later
If you are ordering on a guess, the design you choose matters as much as the size you pick. Some rings have three letters of room in either direction. Some have none at all, and finding that out after the proposal is an expensive way to learn it.
A ring that fits gets worn every day for fifty years. A ring that does not fit sits in a drawer until someone books a resize, which is a fixable problem, and a much smaller one than choosing a ring she does not love.
How far each design can be altered after it is madeCentre line: the size you ordered · Bars: AU letters the workshop can move itRanges are what a workshop will do without compromising the ring. Larger jumps are possible on plain metal, but past about three letters the band is being rebuilt rather than resized, and the proportions of the original design start to go.
This is the quiet reason so many proposals happen with a solitaire on a plain shank. It is a beautiful ring, and it is also the design with the most forgiveness built into it. If she has her heart set on a full eternity band, that can be the wedding ring, ordered later, once you can measure her finger in daylight and ask her opinion out loud.Plain or tapered bandMetal only. Cut, join, polish, done.
3 down · 3 up
Solitaire on a plain shankThe head is never touched. All the work happens under the finger.
2 down · 2 up
Stones down the shouldersThere is bare metal left at the base to work with.
1 down · 1 up
Pavé to the base of the shankStones sit exactly where the cut would go. This is a remake.
No room either way
Full eternity bandEvery millimetre is set. The fix is a new ring.
No room either way
Tension settingThe band is the setting. Change its length and you change its grip on the stone.
No room either way
After she says yes
Ask two questions before you pay for anything: can this design be resized, and what does the first resize cost. Get both answers in writing while you are still a customer being courted rather than one asking for a favour.Then let her wear it for a few weeks before you change anything. Fingers swell in an Australian summer and shrink on a cold morning, engagement week involves more champagne and salt than an ordinary week, and a ring that feels tight the day after the proposal is often correct by the middle of the month. Measure the fit on a normal afternoon, not on the best night of your life.
Working with a guess?Tell us what you have, even if it is only a borrowed ring in a jacket pocket and a hunch. We will tell you what it measures, which designs will still work if the guess is off, and how to keep the whole thing quiet until you want it known.
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