You want it to be a surprise, which rules out asking. Here are the methods that work, in order of how safe they are.
1. Borrow a ring she already wears
The most reliable method. Take a ring from the correct hand, ideally the ring finger, and either bring it to us or measure the inside diameter in millimetres with a ruler. A ring from a different finger is not useless, but it is a guess: an index finger usually runs half to one full size larger than a ring finger.
Borrow it in the evening and return it before morning. Do not take her most worn ring, because that is the one she notices missing.
2. Trace the inside on paper
If you cannot take the ring out of the house, place it on paper and trace the inside circle carefully with a sharp pencil. Photograph it next to a ruler. This is accurate to about half a size, which is close enough when the first resize is free.
3. Ask the friend, not the family
Her closest friend knows and will keep the secret. Her mother knows and will not. This is the single most common way a proposal gets spoiled.
4. Get a ring sizer posted to you
We will post you a plastic ring sizer. The sizer is free and we only ask for $5 postage. It arrives in two to three days, you size a ring she owns at your leisure, and nothing is made until you confirm. If you have three weeks, this is the method to use.
5. Order L and let us resize
L is the most ordered size in Australia and sits in the middle of the range. If you are proposing next week and have no other option, order L. The first resize is free within 60 days of delivery and we pay the postage both ways. She will never know the ring started life a size out.
What not to do
Do not use a piece of string. String stretches and reads about a size large. Do not size her finger while she is asleep, which is both unreliable, because fingers swell overnight, and hard to explain if she wakes up.
When the size is genuinely impossible
Propose with a necklace and choose the ring together. A pendant needs no size, arrives faster, and cannot be the wrong fit. Plenty of people do this deliberately now, and it makes the ring a shared decision rather than a gamble.
Ask us to post a ring sizer, or design the ring first and size it later.
