Tourmaline

Tourmaline is known as the "Rainbow Gem" and that name is completely earned. It's the only gemstone that can come in every single color of the rainbow, and it holds the record for the most colorful gemstone in the mineral world. Its name comes from "toramalli," meaning "mixed gems" in the language of Sri Lanka — a fitting name for a stone that has confused gemologists for centuries. In fact, somewhere in Brazil in the 1500s, a Spanish conquistador washed dirt from a green tourmaline crystal and genuinely mistook it for an emerald. That confusion continued until scientists recognized tourmaline as its own distinct mineral species in the 1800s. It is the state gemstone of Maine and the modern birthstone of October.