Almandine is the most abundant and widely distributed of the six fundamental garnet subspecies and, along with pyrope, one of only two that display the red coloration with which the gem is traditionally associated. This hue arises from the mineral’s inherent iron content, but these ions can be replaced by magnesium to give rise to grape-colored rhodolite garnet and, eventually, pyrope. In much the same way, sufficient replacement of the iron with manganese will instead re-classify the stone as almandine’s orangish isomorph, spessartine.
The species name is derived from that of the ancient city of Alabanda, in modern-day Turkey, which had been a major gemstone trading hub. During this time, almandine garnets were one of several red gem varieties (e.g. jasper, carnelian, etc.) that were referred to as “carbuncles” when cut in the typical cabochon style or, for overly dark-toned material, as a hollow cabochon.