In a TikTok with nearly 2 million views, the Kiara Sky Nails account demonstrates how their color-changing gel polish can switch back and forth between light and dark purples, blues, and pinks when submerged in a bath of ice-cold water. These are thermal nails, meaning that changes in environment or body temperature will set off a very fashionable chemical reaction thanks to one key component: leuco dye. Although the vast majority of thermal polishes have just two color options, a select few brands offer a broader spectrum. KBShimmer, for instance, sells tri-thermal purple, green, and blue paint.

Whereas venturing into an air-conditioned store or jumping into a cold lake in the summertime can trigger a thermal reaction à la mood rings, other nail polishes (much like the viral PH5 dress) react to UV rays. This is called photochromism. The vegan and cruelty-free nail polish brand LivOliv explains that the same effect is used for transition lenses. So brighten up your next at-home or salon mani by opting for thermal French tips, polka dots, or pay homage to the '70s with a vintage swirl pattern.