Confusingly, though, a lot of different products are called “gels.” “It’s a struggle constantly to get the right terminology in place,” Livesay says. “A lot of times people don’t know what they’re asking for.”

There are hard gels, which are the most durable, and can only be removed by filing them off. These are more popular in Europe, according to McConnell. Soft gels are similar, but slightly less durable and easier to remove. Then there are gel polishes, which are more likely to be what the average American will encounter if they just walk into a salon and ask for a “gel manicure.” The composition of these can vary depending on the brand—some are soft gels mixed with solvent; some are gels mixed with lacquer. Both can be removed with acetone.

(A word of caution from Schoon: With any sort of gel, a technician should never file it off all the way down to your natural nail. “This is like putting a bunch of glue on your roof and then taking a crow bar and scraping the glue off. You're going to pull shingles up, too.”)

Gel manicures form the base for a lot of the visual effects that have populated social media of late. “Effect powders” are responsible for the chrome look, as well as the holographic nails. These powders, McConnell says, all work in pretty much the same way, but are just made with different materials. After a nail technician paints on a layer of gel color, they cover it in a special top coat, and cure it under a lamp just long enough for it to be barely sticky. Then they dip the little sponge in one of these powders, and rub it in.

For chrome nails, that powder is made of glass, metal, and pigment. “There’s no chrome in it,” McConnell says. “That would be completely illegal, because chrome is a heavy metal and the FDA would be down our throats about it. It’s more of a mirror nail.” And much like with a real mirror, the reflective effect is created when a metal—silver, in this case—is sandwiched between a base layer of paint (or polish in this case) and a clear protective layer on top (glass for a mirror; a clear, glossy polish for the chrome nails).

The powder doesn’t become a solid, even though it looks like it does; it’s just extremely fine and fills in extremely well. “If you could magnify it really, really large, you could see there’s spaces between each of the particles,” Schoon says, “but you can’t see it with your eye, because they’re too tiny.”

Different effects can be achieved with different pigments. Light Elegance has a bunch of different Pretty Powders, some of which give a chrome effect, some of which are pearly—that comes from mica coated with pigment, McConnell says—and some of which are holographic. The holographic effect (also sometimes called mermaid nail) is made with extremely fine bits of holographic polyester. This look can also be achieved, Schoon says, with a thin polyester film, “like the ribbons they wrap presents in at Christmastime.” But Light Elegance, at least, sells that polyester in a powder form that can be rubbed on the same as a chrome.