While today most people think of Onyx as a pure black stone, in ancient times the name Onyx was used to refer to a wide variety of light colored Agates. The name Onyx comes from the Roman onux, meaning “claw or nail,” which is thought to be a reference to a group of relatively common stones such as Alabaster, Pink Chalcedony, and Onyx Marble, all of which have a soft pinkish-white color, similar to the luster of polished fingernails. In Hebrew, onux means “shining stone.”
According to one Roman myth, Onyx stones had a very unique origin story. When the world was still new, Venus, the Goddess of Love and Beauty, was sleeping on the banks of the sacred Indus River, in India. Her son, Cupid, god of desire, kindly gave her a manicure, using one of his enchanted arrows to do the work. As the nail parings fell into the water, they sank to the bottom and were transformed into Onyx!
Today Onyx is usually thought of as a black stone. It has the rare distinction of being known for mainly negative qualities, rather than positive! According to one medieval lapidary, a text which describes gemstones and their powers, “[Black] Onyx… has bad virtues because he who wears it at the neck or on the back will see devils; it causes many frivolities, brings anger and disagreement, but it gives hardiness.” People were advised to instead wear Sardonyx, or if they intended to wear Black Onyx, to wear Carnelian as well.