Onyx is an oxide mineral with a trigonal crystal structure. The name ‘Onyx’ comes directly from Latin word of the same spelling meaning ‘claw’ or ‘fingernail’. This name stems from the flesh-coloured parallel bands of layered chalcedony that form onyx and resemble fingernails. Although traditionally onyx refers to the black variety, there are other shades. Sardonyx, for example, refers to red or yellow coloured onyx that have been used in jewellery since classical antiquity. Yellow onyx has also been used in lavish interiors. A sumptuous example is a carved Napoleon III bathtub designed by Donnadieu for the Hotel de la Paiva, Paris.