Is it okay to try on someone else's engagement ring for luck?

I don't believe in luck. I believe in ring shanks, knuckles, and gravity. You want to know if it's okay to try on someone else's engagement ring for luck. My answer is yes, mostly, with your hand cupped underneath.

Some families say it's bad luck to try on someone else's engagement ring before your own. I don't carry those rules. I carry a jeweler's saw and a ring clamp, and what I've learned is that bad luck usually looks like a forced fit, a loose prong, or a hard floor.

What I tell clients who want to try on someone else's engagement ring for luck

Go ahead. The gesture is usually kind, and the owner offering it is usually proud of the ring. That part I understand. What I care about is the shank, because a ring sized to one finger will almost never sit right on a different finger, and the moment it doesn't fit, people start pushing.

Don't force it past a knuckle. The knuckle is the widest part of most fingers. If a ring clears it, the band will often spin at the base of the finger. If it doesn't clear it, pushing harder won't help, and forcing a too-small 18k band over a too-big joint can spring the ring slightly out of round, which means the owner's jeweler gets to fix it.

A ring with a high-set solitaire or pavé is the worst to pass around. Every time it slides over a knuckle, the prongs flex. Over years of that, a stone that was tight becomes a stone that rattles, and a stone that rattles eventually falls out on a dance floor or in a parked car where it may never be found. I've re-tipped more prongs than I can count, and I can usually tell which rings were borrowed hard.

Last March a client named Maya brought her mother's ring in after a bridesmaid tried it on over a restaurant sink. The ring went down. It took a plumber, $240, and two hours to recover it, and the center diamond's prongs needed re-tipping before the ring went back on the owner's hand. The diamond survived. The friendship did too, but barely.

If the owner hesitates, don't take it personally. That ring may be insured, but insurance does not cover the exact height of a prong or the memory of a hand that wore it for forty years, and a jeweler's appraisal will not tell you what it's like to fish a ring out of a drain trap at midnight.

Hand lotion, sunscreen, and sanitizer transfer. It's not a reason to skip the luck. It's a reason to wipe the ring with a soft cloth before it goes back. The owner will notice the smear on the underside, and she'll wonder if you noticed it too.

When I'd say no

Don't try on a ring that's already too small for the owner. Don't try on a ring with an illusion setting, micro-pavé, or a thin band under 1.8mm. Don't do it near a sink, a drain, a pool, a boat, a terrace, a dance floor, or a friend's dog. Not because of luck. Because I've seen all of those go wrong in ways that cost more than the superstition was worth.

If she offers, take it. Hold the band, not the stone. Slip it only as far as it wants to go, and cup your other hand underneath. Then give it back. Luck does not resize a band.