The classic colour of garnets is red. The oldest finds of garnet jewellery as grave goods date back to the Bronze Age over 5000 years ago.

Garnet jewellery flourished in antiquity. The Greeks called it anthrakas (after anthrak = coal) and the Romans cabunculus (after carbo = coal), because the stones resembled glowing coals in sunlight. Garnet intaglios in Roman gold, bronze, or iron rings are well known and have been found during numerous archaeological excavations of Roman settlements.

The Roman scholar Gaius Plinius Secundus used the term carbunculus generally for transparent red gemstones, which became “carbuncle” in the Middle Ages.

Albertus Magnus (1193-1280) distinguished three types of carbuncle: balagius (red spinel), granatus (red garnet) and rubinus (ruby). Thus, the modern name garnet first appears in the 13^th century in Albertus Magnus’ book on minerals (De Mineralibus). The name garnet is derived from the Latin granum, meaning “grain”.

In the Early Middle Ages, especially during the Merovingian period, and into the Late Middle Ages, garnet played an important role in jewellery. Famous examples include the Crown of Kech (Kertsch) and the eagle brooch of the Lady of Oßmannstedt from the 5^th century.

The heyday of red garnets began in the 17^th century and lasted until the early 20^th century. Numerous garnet vessels, engravings, and jewellery in important European treasuries and collections bear witness to this. A prominent piece of jewellery is the Order of the Golden Fleece in the Green Vault in Dresden from 1794, a Burgundian order of knighthood containing supposedly the largest Bohemian garnets. Typical garnet jewellery dates from the Biedermeier period (1815-1870), the Victorian period (1837-1901), and the Art Nouveau period (1890-1910).

Fig. 2: Brooch with Bohemian garnet (pyropoe). Early 20th century. Collection of Hermann Lind II, Idar-Oberstein, photo by U. Henn.

Mineralogically, the classic red garnets belong to the complete solid solution series pyrope-almandine. The pure end-members pyrope (Mg₃Al₂(SiO₄)₃) and almandine (Fe₃Al₂(SiO₄)₃) are rare, and are not encountered in gem quality. In the gemstone trade, magnesium-rich specimens are referred to as pyrope, and iron-rich ones as almandine.

The magnesium-aluminium garnet pyrope owes its red colour to traces of chromium (“chrome pyrope”) and/or iron. It was named by Werner (1803) from the Greek pyropos, for fire-eyed or fiery. Bohemian pyropes, whose existence was already known in the Middle ages, became world-famous in the 18^th century. Regular mining already took place in the 16^th and 17^th centuries. The centre of processing into typical Bohemian garnet jewellery, which is nowadays largely important for tourism, is the town of Turnov (formerly Turnau), northwest of Prague. The rough crystals are usually small, with a diameter of up to 6 mm. The average size of polished stones is therefore 1 to 5 mm.

Pyropes from the diamond-bearing kimberlites of South Africa were long called “Cape rubies” because of their blood-red colour.

Fig. 3: Almandine in mica shist. Zillertal, Austria. Image width approx. 6 ct, collection of DGemG, photo by T. Stephan, DGemG.

Almandine is an iron-aluminium garnet and owes its name to Agricola (1546) after the town of Alabanda on the Mäander River in Turkey. The deposits in the Zillertal and Ötztal regions of Austria, discovered by a poacher in 1745, are of historical significance. The heyday of Zillertal garnets was the mid-19^th century, when they were processed into traditional garnet jewellery (traditional costume jewellery), which still enjoys regional significance today. Due to heir high iron content, the crystals found in mica shists are very dark and usually appear black, thus opaque. When reduced to smaller dimensions, they acquire transparency and a deep red colour.

India (“Indian garnet”) has been an important supplier of almandine-rich garnets for the jewellery production for centuries. Significant deposits are in the state of Rajasthan, with its capital city of Jaipur. Large star garnets, which can weigh several hundred carats when cut, are found near Hyderabad.

At the beginning of the 20^th century, vibrant red garnets from East Africa, present day Tanzania, first appeared on the market. The darker Madagascar garnets followed a few years later. Other commercially important deposits of red garnets are Thailand and Mozambique.

Garnets can occasionally reach gigantic sizes, but these are not suitable for cutting. The largest garnet ever found comes from Norway. The irregular shaped garnet block has a diameter of 2.3 meters and weighs 37.5 tons. Several large, well-formed garnet crystals are on display in various museums around the world and can reach sizes of up to one meter.

Fig. 4: Faceted almandine, 5.26 ct. Collection of DGemG, photo by T. Stephan, DGemG.

One of the largest processed garnets is an egg creation by Manfred Wild from Kirschweiler, Germany, designed in the style of famous Fabergé works of art. The two halves of this perfectly cut egg are made of red garnet from India, weighing 5.696 ct.

The Medici Collection in Los Angeles, USA, houses a 3.956 ct star garnet, which was listed on the Guinness Book of Records in 2020. The largest known cut almandine to date is a 175 ct cabochon in the Smithsonian Institution in Washinton, USA.

Among those of historical significance are the pigeon-egg-sized pyrope from the treasury of Emperor Rudolf II, mentioned by Boethius de Boodt in his 1609 “Historia gemmarum”, and a chicken-egg-sized pyrope (468,5 ct) in an Order of the Golden Fleece in the Green Vault in Dresden.

Author

Dr. Ulrich Henn, DGemG
© 2024