Onyx

Black glass polished to a mirror, Onyx carries the weight of its namesake stone, a banded chalcedony the Greeks associated with fingernails and fierce protection. The name has surged in the past decade alongside a broader parental appetite for gemstone and color names that read tough rather than precious. That hard final X gives it a rock-star edge, while its unisex register keeps it from settling into either expected register. Once reserved for superheroes and racehorses, Onyx now rides comfortably inside the U.S. top 400. Sleek, modern, slightly dangerous, it lands like a stone dropped into still water.