How to Secretly Measure Her Ring Size: The Ultimate Guide for a Surprise Proposal

Planning a surprise proposal is one of the most exciting—and nerve-wracking—moments of your life. You’ve found the perfect partner, the perfect ring, and the perfect moment. But there’s one small (yet crucial) detail standing between you and that picture-perfect “yes”… her ring size.

Guessing wrong could mean the ring doesn’t fit during the proposal, which can take a little shine off the big reveal. Don’t worry—our experts at Mark’s Diamonds in Denver have mastered the art of how to secretly measure ring size without spoiling the surprise. Here’s how to get it right, discreetly and confidently.

Method 1: The Easiest Way to Secretly Measure Her Ring Size — Borrowing a Ring She Already Wears

When it comes to covert operations, this is the smoothest method.

The Strategy: When to “Steal” the Ring

Keep an eye out for jewelry she doesn’t wear every day—perhaps a ring she wears on her right hand. Borrowing one she wears constantly might raise suspicion. The trick? Wait until she takes it off for a shower, workout, or cleaning.

Pro tip: Always make sure it’s a ring she wears on the correct finger (the ring finger on her left hand is ideal). Fingers on the right hand can vary slightly in size, so the fit won’t be perfect but should be close enough for the proposal.

The Measurement: The Paper, or Ruler Trick

Tracing the Inside of the Ring

Lay the ring flat on a piece of paper and trace the inside edge with a pencil. The jeweler can use this to determine the diameter.

The Warning: Ensure It’s Worn on the Ring Finger

A ring worn on the middle or index finger will likely be too big, while a pinky ring will be too small. The ring finger on her left hand gives the most accurate measurement for engagement rings.

Method 2: The Subtle Approach — Using Her Friends or Family

If stealth isn’t your strength, enlist a little help.

Enlist a Trusted Accomplice (Mother, Sister, Best Friend)

Ask someone close to her—especially someone who can be trusted to keep a secret. A best friend or sister might already know her size, or can cleverly find out without raising suspicion.

The “Try-On” Trick

Have your accomplice pretend they’re shopping for themselves. They can casually ask your partner to “try on” a ring while comparing finger sizes. Sneaky, simple, and highly effective.

Method 3: The Hands-On, High-Risk Approach

Feeling brave? These methods work—but proceed with caution.

Measuring While She Sleeps

If she’s a deep sleeper, you can gently wrap a piece of string or thin strip of paper around her ring finger. Mark where the ends meet, then measure it against a ruler. However, note that this method can be inaccurate and risky—one wrong move and your surprise might be exposed!

Comparing Your Own Fingers to Hers

A surprisingly effective (and funny) method: see which of your fingers her ring fits on. If it slides comfortably to a certain joint, your jeweler can estimate her size based on that comparison.

The Critical Next Step: Converting Your Secret Measurement to a Size

You’ve gathered your evidence—now it’s time to make it official.

Why You Need a Professional Jeweler’s Help

Home measurements are just a starting point. Bring your notes, photos, or impressions to a trusted jeweler who can make accurate adjustments before the ring is ordered. Professionals can also resize a ring perfectly after the proposal, ensuring a flawless fit.

If you ever need resizing or adjustments, our team at Mark’s Diamonds jewelry repair experts are here to help you restore or resize cherished pieces with precision and care.

Mark’s Diamonds’ Exclusive Ring Sizing Guarantee

We understand that surprises come with a bit of guesswork. That’s why Mark’s Diamonds offers complimentary resizing on engagement rings purchased through our store. If the ring isn’t a perfect fit on proposal day, we’ll make it right—quickly and professionally.

Ready to Propose? Schedule a Private Consultation Today

Your proposal deserves a ring that fits perfectly—in style, size, and sentiment. At Mark’s Diamonds, we specialize in helping clients plan unforgettable proposals, offering expert guidance and private, one-on-one consultations in our Cherry Creek showroom.

Let’s make your surprise proposal stress-free, seamless, and absolutely unforgettable. Schedule your private consultation today and find the perfect engagement ring to match your perfect moment.