It's a surprisingly common faux-pas.

Perri Ormont Blumberg
February 16, 2018
Trumpet & Horn/@trumpetandhorn

You've known what setting you wanted for your engagement ring since third grade. Heck, you've known what color manicure you'll get to complement your ring after he pops the question since fourth. But have you thought about the so-called "longevity" factor of the diamond itself (that is, will 64-year-old you like that pear-shaped stone)? Probably not.

One top jeweler on instagram, Stephanie Gottlieb, thinks this consideration should be an important part of engagement ring shopping — and something couples opften overlook.

"A lot of people don’t think about the longevity of the piece," Gottlieb said in a recent interview on Elite Daily. "You want to make sure that you’re picking a stone that you’re going to love for a long time." As times goes on, you may decide you want to change your ring's setting, but you can't change the actual stone (unless, of course, you buy a new ring). 

WATCH: 100 Years of Breathtaking Engagement Rings

Along with that, Gottlieb also feels that many forget to take into mind the quality of the stone as it compares to its size. "Some clients select the biggest size possible, compromising on quality all together because they’re concerned about how big the stone looks," explained Gottlieb. "But once you see the yellow in a stone, or an imperfection becomes visible to you, those things will never go away."  Alas, what would Kate Middleton do?