Onyx
It should be relocated at Black because This colour name isn't mentioned in the sources cited, better to be covered on the page for the colour black.
Talk about it here or check the revision history for additional comments.
Onyx was a shade of black, which shared its name with a gemstone.
Captain Latimer wore an onyx black cravat in 1892. (TV: The Snowmen [+]Loading...["The Snowmen (TV story)"])
John Lumic wore an onyx black cravat up to when he was converted into a Controller of the Cybus Cybermen. (TV: Rise of the Cybermen [+]Loading...["Rise of the Cybermen (TV story)"], The Age of Steel [+]Loading...["The Age of Steel (TV story)"])