We’ve heard it umpteenth times: Diamonds are a girl’s best friend, at least according to showgirl Lorelei Lee. Now, it seems the shiny, pricey rocks are making fast friends of skincare shoppers looking to upgrade their bathroom cabinets. 

111SKIN, founded in 2012 by plastic surgeon Yannis Alexandrides, offers a collection of serums, creams, and masks formulated with diamond powder. The most expensive product in the “Intensive” line — Celestial Black Diamond Cream, a moisturizer that purports to plump wrinkles, even skin tone, and stimulate collagen production — will set you back $665. It’s not far off from competitors like Omorovicza’s $420 Blue Diamond Super Cream and KNESKO’s $155 Diamond Radiance Collagen Face Mask. These ultra-luxe products look good, and boast descriptions that sound even better. But are they really the secret to a 100-carat glow?  

Diamonds aren’t exactly new to the world of dermatology. Geeta Yadav, board-certified dermatologist and founder of FACET Dermatology, says the stones are particularly effective exfoliators thanks to their hardness (in fact, diamonds are some of the hardest materials on Earth). When ground to a powder and applied to the skin, the gems act like a scrub, sloughing off dead skin cells to reveal a brighter, smoother surface beneath. 

Those seeking microdermabrasion, a medical-grade exfoliation technique, might come face-to-face with a diamond-tipped wand, often used to buff the stratum corneum (the outer layer of skin). “Skincare professionals can adjust the intensity of the treatment by using different diamond tips, making it suitable for various skin types and conditions,” says cosmetic chemist David Petrillo, founder of skincare brand Perfect Image. “Diamond microdermabrasion provides more uniform exfoliation than other methods, like traditional scrubs or chemical peels. This uniformity reduces the risk of uneven skin texture or damage.”

Size matters when dealing with diamonds — and in this case, the smaller, the better. Aside from exfoliating, diamond powder doesn’t do much. “Diamonds granules and powder are too large to penetrate skin effectively,” says Rachel Nazarian, a board-certified dermatologist at Schweiger Dermatology Group . That said, they can have surface-level perks. In some cases, Dr. Yadav says, diamond creams and serums can “help reflect light and give the skin a more luminous quality.” 

Nanodiamonds, diamond particles that measure below 100 nanometers, are less visually impressive than the sparkly stones serenaded in Gentlemen Prefer Blondes, but might make better skincare allies. “Nanodiamond particles are super, super, super small particles of diamonds which have potential for a slew of medical and dermatological applications,” Dr. Nazarian says. “These nanoparticles are capable of penetrating skin to deep levels, but also enhance the absorption of surrounding ingredients that are paired with it.” Nanodiamonds also show promise in drug delivery systems and wound healing. Thanks to their large surface area, they can be used to carry medication, “allowing for controlled release and targeted delivery of drugs for various dermatological conditions,” Petrillo says, adding that the antimicrobial properties of nanodiamonds “may help reduce the risk of infection in wounds and promote faster healing.”

111SKIN — a favorite among celebs like Kim Kardashian, Bella Hadid, and  Victoria Beckham — doesn’t advertise its use of nanodiamonds, but a representative confirms that they are indeed the backbone of the brand’s Intensive line. “[Nanodiamonds] have been well-known for many years in medicine as carriers of active ingredients,” Dr. Alexandrides says. “I thought, ‘Why not apply this same principle to skincare?’” He adds that the microscopic particles are biocompatible, “meaning they aren’t toxic to humans, and their structural makeup makes them able to pass through the body and the skin in a variety of ways. The [nanodiamond powder] we use at 111SKIN is so fine that it helps boost circulation, readying the skin for topical skincare.”

The allure of diamonds makes it easy to assume that any skincare product containing the sparkly gemstone must work. But to Petrillo, brands that tout the ingredient “may be more about marketing and perception of luxury rather than scientifically proven skin benefits.” If you’re going to drop serious money on diamond-powered skincare, make sure you understand how the stones are being used and for what purpose: If you’re in the market for an exfoliator, opt for a product with diamond powder; if you want a serum that will deliver active ingredients effectively, choose one that has nanodiamonds. We also suggest doing your own research on the socioeconomic implications of diamond harvesting, an issue that might inform whether you opt for beauty brands that use natural or lab-grown diamonds.

As to whether the dermatologic benefits of diamonds are worth hundreds of dollars per ounce of cream, serum, or other goo? A hint might be found by revisiting Gentlemen Prefer Blondes, the book and musical that forever linked diamonds, girls, and friendship: It's simply a matter of personal preference.