The faceted spindles of Onyx (gef.) are about 1.2cm long and 0.6cm thick; the total length of the onyx strand is about 40cm.
The name Onyx is derived from the Greek word "onyx" meaning "nail"; presumably this name, which has been in use for many centuries, refers to the surface of the polished stone, which resembles shiny fingernails. Spellings like onix or onyk are therefore not correct.