escarboucle

OBS: À l'époque de Molière, on appelait «escarboucle» le grenat rouge foncé d'un éclat vif.
OBS: Autrefois, pierre précieuse brillant d'un vif éclat rouge.

OBS: The term carbuncle may also have a second meaning and be an old name, now obsolete, for any of several precious stones of a fiery red colour such as ruby or spinel.
OBS: One of the world's most ancient gems, garnet was called carbuncle by early civilisations. Today, however, carbuncle refers only to red cabochon cut garnet.