Faux black glass
It is interesting that these plastic buttons, so obviously imitating faceted black glass, were still being sold around 1965. They appeared in an October 1952 advert, where it was labelled ” the faceted Jet Beutron” and also in an October 1953 advert.
These are copies of black glass buttons, which in turn were copies of the real jet (fossilised wood) buttons as worn by Queen Victoria. She wore “mourning” clothes including jet buttons and jewellery for the rest of her life after the death of her beloved Albert on 14th December 1861. It should be noted that black glass and jet buttons for mourning preceded this. In the ‘Lady’s Magazine’ for July 1830, the use of jet jewellery and buttons was described for mourning. As noted by Charles Dickens noted in his report published in the Penny Magazine on the 24th November 1838:
Faceted glass were made by hand cutting sheet glass until mechanisation took over. Later, moulds were used to give the appearance more easily.