So you sly devil, you are going in for the surprise gift! Kudos. Along with this romantic bravery, you will need to get an idea of his or her finger size, and this can be tricky! 

To help you keep the surprise exactly that, I have come up with a few spy worthy tactics to help! 

1, Daylight robbery. 

Borrow one of her rings. If you are lucky enough to have a partner that wears lots of rings, they are going to make things easy for you. Take note of what rings are worn on which fingers, and then as soon as the opportunity arises, snag the appropriate ring finger ring. If you can borrow it long enough to bring it into a jewelers, they can get an accurate measure from this ring. If however, he/she is the type to notice and turn the house upside down in looking for it, there are a few things you can do at home. 

• Download our ring sizer and print it out at 100% (That is very important, it must be printed at 100% to scale), and use “The Secret Test” to lay the ring over and find a match. The match should perfectly fit along the inner edge of the ring with the full circle visible.
• Push that ring on to your own fingers and mark where it gets snug. Start on your pinky, does it fit? Is it loose? Then try your own wedding finger, where does it get to before it gets tight? Make a pen mark. Then try your middle. With these marks on your fingers, pop into your local jeweler for help! 

If she/he doesn’t have a ring that they wear on that finger, it’s okay, we can make a close estimate based on another ring, so if it's a pointer or middle finger ring, take note of which finger this is for, and do the same sleuthing. We will be able to get you close.

2, Call in the allies. 

Girls dream and girls talk, so there is a good chance she has discussed jewelry with her nearest and dearest. If you can trust them, it’s time to enroll them! There are a few ways they will be able to help. 

• They may have actually gone shopping together already, usually, this happens when one of their circle is getting engaged or close to it, and often girls like to have their own size taken while there. So ask her bestie/ sister/ partner in crime if this has ever happened. 
• They may have tried on a friend’s engagement ring or other rings. The best friend usually has an idea of their comparative sizes, if her jewelry fits your lady for example, or if she is smaller or bigger. This is a good place to start. 
• If you really really trust one of her crew to play this cool, ask her to casually pop into a jeweler the next time she is out brunching with your girl. Perhaps one of her crew is getting engaged or married soon, and she can ask your lady to accompany her while shopping, and nonchalantly ask if she knows her size while at it. And if not, she can throw in a “you should get measured, I feel like that's something that’s good to know”. Now, not all can pull this off, so you have to use your intuition here as to who of her friends has the best poker face, and is vested in your secret. 

3, Spike her dinner with Nyquil*

*Disclaimer, we are ABSOLUTELY just kidding. However, the next suggestion is very risky, and will only work if your other half is a very deep sleeper! The string test. While they are sleeping, use a fine thread or piece of string and wrap it around her wedding finger, or the desired ring finger. Not too tight, as it has to get over the knuckle. But marking that string, measure the length on a ruler. Our Ring Sizer has a conversion guide to help you. 

4, The paper cut test. 

Again, this will only work with a heavy sleeper. If the string test appears too vague, we have an alternative that might help. Print out our Ring Sizer at 100% (again, 100% scale is very important) and cut out the ring sizer under “The Paper Test”. Make a small slit where the guideline suggests. Wrap the sizer snugly around the widest part of their finger so that the numbers are visible to you, and insert the pointed end through the slit you made. The number that aligns with the slit is going to be close to the proper size. 

5, Guestimations and Calculations.

Here we are getting down to guesswork, but all these details help. The average New York woman’s wedding ring finger size is 5.5 to a 6. This differs a lot US and Globally, but in New York 5.5 / 6 tends to be the most common size. So knowing that, how does your girlfriend compare to her friends? Is she slimmer or shorter than most? Is she especially petite or does she have strong hands? Again, ask her friends, does she fit their rings? 

Then compare her hands to your own. Take her hand during the next episode of Ozark, and study hers in relation to yours. Which of your fingers looks closest in size to her wedding finger?

The more groundwork you can do, the better, as resizing will mean extra shipping and expense, however, do not fear, we will get you close. Feel free to email photos of your partner (photos where their hands are clearly visible) as a last resort, and we can make an experienced guestimate. 

Good luck! You got this!