Garnet – January Birthstone
Garnet is the name of a family of minerals, which similar crystal structure and related chemical composition. They grew in popularity in the late 18thC and are still widely used today, in either cut or polished cabochon form. Garnets are popularly believed to be red stones, but this is not always the case. Not only are garnets found in a whole variety of red hues, but also in green (though these are rarer). The main representatives of the garnet family are:
- Pyrope (or rhodolite), is the most commonly used garnet today, and it was mined in enormous quantities in 19thC Bohemia. Therefore, the majority of 19thC rose-cut garnet jewellery on the market today is Bohemian, and stones are normally mounted in simple, low-carat gold or base metal settings. Usually pyrope garnets are attractive deep claret red, and are popular today for use in mass-produced jewellery.
- Almandine garnets, have a more purple hue than pyropes, and were often used in polished cabochon form in 19thC Holbeinesque and Renaissance Revival jewellery, as well as in formal parures. The polished cabochon treatment creates a deep, luxurious effect. Many almandine garnets were foil-backed in the 19thC to enhance their colour (and these always have closed-backed settings). Though the almandine garnet shown here has inclusions, many gems used in the 19thC were flawless. The stones are not particularly valuable in their own
right, but when incorporated into a good piece of jewellery, they can be very desirable.
- Grossular garnets (also known as “Tsavorite”), found in South Africa, Mexico and Oregon, are less common than pyropes and almandines. In its purest form, the grossular garnet is colourless, but is more often a yellowish brown, reddish pink or, most famously, green. While the green grossular garnet looks similar to the much rarer demantoid garnet, it lacks the latter’s brilliant lustre. Often these stones have an almost oily appearance when looked at under a Ioupe, due to their oily inclusions, known as “treacle”.
- Demantoid garners are the rarest and most valuable of all the garnet family. Discovered in the late 1860s in the Ural mountains, demantoids range in colour from a dark emerald to a pale yellow-green. Apart from a characteristic brilliance, demantoids can be identified by their fibrous asbestos flaws, called “horserails”.
Any stones over 2ct that have a good clarity are extremely rare and valuable.