You are about to buy the ring, but you don’t know her ring size. Don’t ruin the surprise by asking her what her ring size is. There are several ways to know her ring size while still keeping it a secret.

Get someone who may already know what ring size she wears. You may ask her flatmate, sister, best friend or even her mom. Even if they don’t know, they can find out without her suspecting a thing.

If she is the kind of person who is into rings or jewelry, pay attention to the rings she wears. If she has one that fits on her left ring finger, wait for her to remove it and take it to a jeweler to be sized. If she only takes it off to work out or shower and you have limited access to the ring, buy a bar of soap and press the ring in to make a mold. Your jeweler should be able to use the markings to identify the correct ring size.

If she literally only takes her rings off to lotion her hands for five seconds, slip the ring on your finger and note exactly where it fits on your finger. Using the various ring size charts and sizers, you or a jeweler should be able to replicate the fit.

And when all else fails, go for a larger size; it’s easier to resize a ring smaller than it is to go bigger.

Jewelers’ Ring Sizing Tips

Try these tricks of the trade to find the perfect fit. Jewelers believe that you should

– Go for a snug fit: The ring should go on easy and come off hard. This means you have the right fit and the ring is sized properly for the finger, minimizing the risk of loss.

– Keep seasons in mind: Your fingers tend to change size throughout the course of the year. They’ll swell up a bit during the dry season so keep that in mind so the ring doesn’t become uncomfortable to wear during those months.

– Consider the width of the band: The wider the band, the tighter it will fit. Jewelers recommend going up .25 to .5 size for rings with wider styles.

– Warm up your hands: If you’ve just come in from the cold or naturally have colder hands, you are advised to warm them to room temperature for the most accurate sizing.

– Go big: If you get two different finger measurements or find that a ring you wear often fits differently from time to time, it’s best to choose a slightly larger size, and, if you can, consult a professional.