Garnet and carbuncle: red stones that glow like embers

In antiquity and the Middle Ages there was no precise distinction between the various red stones. Garnets, rubies and spinels were often called by the same name: anthrax in Greek, carbunculus in Latin, meaning a small glowing coal. The idea was that these gems held an inner fire, able to shine even in the dark. From this image arose protective beliefs and legends of luminous stones that travelled through the cultures of the Mediterranean and of northern Europe.

The carbuncle of Theophrastus and Pliny

Theophrastus describes anthrax as a red stone which, held against the sun, takes on the colour of a burning coal, and notes that very valuable seals were made from it. Pliny the Elder, in the thirty-seventh book of the Natural History, distinguishes several varieties of carbunculus by origin, including India, Ethiopia and the region of Carthage, and by colour, calling the most vivid ones male and those with a softer light female.

The name garnet became established later, in medieval Latin, and is generally linked to the pomegranate, malum granatum, because of the resemblance between the small red crystals and the seeds of the fruit. Albertus Magnus, in De mineralibus, treats granatus and carbunculus separately, giving the latter the most intense light of all stones and the ability, according to tradition, to shine in the darkness.

The shining stone of the ark

Belief in gems that light up the dark is also found in Jewish tradition. In the book of Genesis God orders Noah to make a tsohar in the ark, a word usually translated as window or opening. Some ancient rabbinic commentaries interpreted it instead as a shining precious stone, hung in the ark to light the voyage during the flood. The story enjoyed lasting success and contributed to the carbuncle's fame as a stone that glows in the night.

The garnets of early medieval warriors

Between the fifth and seventh centuries garnets, imported largely from India and Sri Lanka, became the characteristic material of Germanic goldsmiths' work. The cloisonné technique set thin slices of garnet into gold cells, producing glowing red surfaces. The grave goods of the Sutton Hoo ship burial in England, excavated in 1939, include buckles and clasps of this kind, now in the British Museum.

These jewels were both marks of prestige and, very probably, objects charged with protective value, although the written sources of the time say little about their precise meaning. Red, the colour of blood and fire, suited the image of the warrior and the chieftain well, and the light the slices reflected under the torches of the halls must have heightened the effect.

The history of garnet is thus bound up with that of a name, carbuncle, and of an idea, the burning stone. Theophrastus and Pliny described its appearance, rabbinic commentators and medieval lapidaries made it a light in the darkness, Germanic goldsmiths used it for the insignia of their leaders. The virtues attributed to these stones are traditional beliefs, but their visual appeal explains well why they lasted so long.