January birthstone – garnets

Happy New Year everyone! Let’s start off 2022 by looking at a beautiful gemstone, the garnet.

The garnet is the birthstone for those born in January. Garnets are unusual as they comprise a loosely connected species of gemstones which have different chemical compositions, but which can be divided further into different varieties which have the same crystal structure and similar properties. Generally, the colour of a garnet is determined by its chemical composition. They come in in a range of colours – pink, red, purple, orange, black, yellow, and green. Those with iron or manganese in their composition are likely to be red, while those with calcium are inclined to be green.

Garnets in the pink to red colour range are the most common garnets. Almandine garnets are generally a very dark red while pyrope are a fiery red. Mixtures of garnets are common, resulting in almandine-pyropes, such as the rhodolite which is a pinkish mauve colour, and pyrope-spessartines (an orange-red).

Garnets with calcium in their chemical composition include demantoid, a green garnet, hessonite, a yellow, and tsavorite, a rich green. The photos I have included in this post, however, are all in red to pink shades.

Almandine and pyrope garnets were used in antique jewellery and have been for centuries. It is important to note that garnets, particularly cabochons, were usually foiled, that is, they were mounted in closed back settings with a small sliver of tinted copper (in the Georgian period), foil made from a leaf of tin (19th century) or aluminium foil (from 1910 onwards) behind the stone or lining the setting. Foiling enhanced the colour and brilliance of the stone. Even when open settings became common for gemstones in the 19th century, foiling of garnet cabochons continued throughout the century.

Pyrope garnets were used in Bohemian garnet jewellery in particular. Craftsmen in 19th century Bohemia (later part of Czechoslovokia) began to produce jewellery using pavé-set clusters of multi-faceted stones. This jewellery was mounted either in gold, often low grade,  but also in silver gilt or metal. Typical designs used rose cut garnets clustered around a garnet cabochon in star shaped patterns or flowerheads, with the settings were usually  closed at the back.

Garnets are still popular today, with the red garnet cabochon still as gorgeous and striking as ever.