The spindles made of polished black Onyx are about 14mm long and 8mm thick; the whole onyx strand has a length of 40cm.
The name Onyx is derived from the Greek word "onyx" for "nail"; presumably this name, which has been in use for many centuries, refers to the surface of the polished stone, which is reminiscent of shiny fingernails. Spellings like onix or onyk are therefore not correct.