How to Find Her Ring Size Secretly for a Christmas Proposal

So you've found the one, picked the moment, and maybe even scouted the perfect spot by the water for Christmas Day. There's just one small detail standing between you and a flawless surprise: you have no idea what her ring size is. Don't panic. Working out how to find her ring size secretly is one of the most common questions we hear in the lead-up to proposal season, and there are some clever, low-risk ways to do it.

Here's our guide to getting it right without giving the game away, plus a few Aussie-summer quirks worth knowing before you place your order.

First, a Quick Word on Australian Ring Sizes

In Australia (along with the UK and New Zealand), ring sizes are measured in letters rather than numbers, running from A through to Z, with half sizes in between, such as L½ or N½. If you come across a US size online (a number like 6 or 7), it won't match up directly, so always convert to the Australian letter system before you order.

It helps to know that a single size up or down makes a noticeable difference. A ring that's "nearly right" can spin, pinch or slide over the knuckle, so it's worth a little detective work.

How to Find Her Ring Size Secretly: Five Tried-and-True Methods

1. Borrow a ring she already wears

This is the gold standard. Pick a ring she wears regularly, ideally on her left ring finger or the same finger on her right hand (fingers can differ slightly hand to hand, so the left is best). Borrow it for an hour when she won't notice, then bring it to us or measure the inside diameter in millimetres with a ruler. Make sure it's a ring she wears, not one tucked away in a drawer for years.

2. Trace it or press it

Can't take the ring out of the house? Trace the inside circle onto paper with a sharp pencil, or press it gently into a bar of soap or a ball of Blu Tack to capture the inner edge. Trace both the inside and outside if you can. Our team can work from a clean tracing to give you a good estimate.

3. Recruit an accomplice

Her best friend, sister or mum is your secret weapon. They can casually suggest trying on rings while out shopping, or bring up ring sizes in conversation ("I've just found out I'm an M, what are you?"). Just make sure your accomplice can keep a secret until Christmas.

4. The string or paper strip method (with caution)

If she's a heavy sleeper, you might be tempted to wrap a thin strip of paper around her finger and mark where it overlaps. It can work in a pinch, but paper stretches and string is notoriously inaccurate, so treat the result as a rough guide rather than gospel.

5. Make an educated guess, then size after the "yes"

If all else fails, choose a size based on her build and the rings you've seen her wear, then plan to have it adjusted after the proposal. Many people actually prefer this route, because it means she gets to be part of the final fitting.

Aussie Summer Tip: Heat Changes Everything

A Christmas proposal in Australia usually means warm weather, and fingers naturally swell in the heat and shrink in the cold. A ring that slips on easily on a cool morning might feel snug at a Boxing Day barbecue. If you're measuring her finger directly, aim for the end of the day at room temperature, and avoid measuring straight after exercise or a hot shower.

Band width matters too. Wider bands tend to feel tighter than slim ones in the same size, so if you're considering a chunkier style, mention it when you share her size with us.

Choosing a Ring That Makes Sizing Easier

Some styles are more forgiving if you're not 100% sure on size. A classic solitaire on a plain band is generally simpler to adjust after the fact than a full eternity design or a band covered in intricate detail.

The Oval Cut Lab-Grown Diamond Compass Prong Solitaire Ring is one of our most-loved engagement rings, and its clean, timeless band makes it an easy pick if you're working from a best guess.

If she loves a little hidden detail, the Oval Cut Lab-Grown Diamond Hidden Halo Solitaire Ring pairs a flattering oval with a secret sparkle beneath the centre stone, visible only from the side.

For the nature lover

If she's happiest outdoors, our nature-inspired rings are made for her. The Dutch Marquise Lab-Grown Diamond Nature Inspired Vine Detail Ring wraps an elongated Dutch marquise in delicate vine-like detailing. With a detailed band like this, it pays to get her size as close as you can before you order.

Something new for summer

Want something she won't have seen everywhere? The Dutch Marquise Lab-Grown Diamond Floating Bubble Band Ring is one of our new engagement ring styles for 2026, pairing the elongated Dutch marquise with a playful bubble band.

Don't Leave It Until the Last Minute

Made-to-order lab-grown diamond rings take time to craft, so if you want your ring before Christmas, place your order by 18 November. That means starting your sizing mission now rather than the week before. The earlier you have a size (or even a good guess), the more choice you'll have and the less stress you'll feel on the big day.

Ready to Plan Your Proposal?

Whether you've got a borrowed ring, a soap imprint or just a hunch, our team is here to help you find her ring size secretly and choose a ring she'll love. Book an appointment at our Kirrawee showroom or browse our lab-grown diamond engagement rings today, and let's make this Christmas one to remember.