You always want what you can’t have — especially when it comes to beauty products. That’s why we’re getting the inside scoop from your favorite retailers on what’s selling out right now, how to sign up for waitlists, and where to go to find the next best thing. Because if everyone’s buying it, you know it has to be good.

In 1513, Juan Ponce de León discovered the fountain of youth — at least, that's what he thought. Reportedly, the everlasting deposit of water was found somewhere in Florida (no, not in modern day Disney World), and while historians never actually proved whether or not León had actually discovered said place, it's hard to deny that he set out to do what many people had hoped to for centuries before him: stop aging.

Alas, it's 2018 and our version of the life-preserving liquid doesn't come from a conquistador. Instead, we satisfy our obsession with aging with skin-care trends, like buzzy new cosmetic procedures or human growth hormones. But there's one beauty trend that sets out to help you find your own fountain of youth, without needles or the foreskin of a baby's circumcised penis. Better yet, it's straight from South Korea. Enter: glass skin.

“Glass skin is this idea of transparent and translucent skin” Alicia Yoon, founder of Peach & Lily, explained to us back in 2017 at the height of the trend. “It's a sign of youthfulness and it's one of the most strived for qualities in Korea." Yoon described it as "the pinnacle of youthful skin" and, a year ago, claimed that products alone won't help you achieve the super-smooth complexion overnight — at least, until she went ahead and formulated one to help get you there.

Peach & Lily's new eponymous skin-care line recently launched its Glass Skin Refining Serum, that predictably, sold out almost immediately (once on the brand's site and once on Ulta Beauty). Now, the refining serum is sold out again and won't be restocked for a few weeks. To satiate your craving for "glass skin," we've found the best alternatives to try until this serum is back online.

Click ahead for the smoothing, firming, and hydrating serum's best dupes.

There is a lot of product out there — some would say too much. At Refinery29, we’re here to help you navigate this overwhelming world of stuff. All of our market picks are independently selected and curated by the editorial team, but if you buy something we link to on our site, Refinery29 may earn commission.