The birthstone for those born in January is garnet, a gemstone with an exciting array of colours and varieties to choose from. Most people know the dark red stone that can be found in every jewellery store, but the garnet family is also home to some much rarer, very beautiful and desirable varieties. Read on to find out more about this fascinating gemstone.
The varieties of garnet form what gemmologists call an isomorphous series. This means that different trace elements, such as magnesium or iron, can replace each other in the crystal’s structure without altering its shape or pattern. The properties of the crystal are altered though, giving variation in colour, the way the stone interacts with light and how hard it is, producing a fabulous range of options for the prospective purchaser.
The classic reds are the almandine and pyrope varieties which can mix and blend together to form a continuous spectrum from brownish-red to purplish-red. These rich, regal colours can be very beautiful, and a popular mixture is rhodolite garnet which is a very attractive purplish-red raspberry hue.
Due to the replacement of different elements in the crystal structure the blend of colours continues from red through to oranges and yellows. These are usually spessartite garnet, which can have bright and striking orange hues, and often forms as a mixture with the red varieties. Hessonite garnet is another variety that occurs in golden to brownish hues and has a distinctive ‘treacly’ internal appearance.
The garnet family is home to two green varieties that are very desirable and can be among the more expensive of coloured gemstones. The first is tsavorite garnet. This stone receives its colour from the presence of chromium and vanadium within the crystal. These are the same elements that give emerald its famous green, and they produce a similar colour in tsavorite. In fact, if you are looking for an intense green gemstone with good clarity and sparkle, then tsavorite can be a more suitable stone than emerald. The only drawback with tsavorite is that it doesn’t form in large sizes: most stones are less than a carat in weight.
Demantoid garnet can be the most valuable and desirable of all the garnets. It is also green, and receives its colour from chromium and iron, this gem generally has a more muted colour than tsavorite, although the finest stones can have a very vibrant colour. What makes demantoid special is its ability to disperse light. This is the phenomena you observe when a prism produces a rainbow: each colour is bent by a different amount as it enters the prism allowing the colours to be seen individually. In highly dispersive gemstones this causes flashes of colour to be seen: the effect is known as fire and is one of the properties that makes diamonds so beautiful and popular. Demantoid has a greater ability to disperse light than diamond does, and although this is to an extent masked by the colour of the stone, it adds an extra element to the beauty of the stone.
Garnet is a reasonably hard gemstone that can be worn regularly, although rings should be removed for activities such as housework, DIY or going to gym as the stone can become scratched or abraded over time. Demantoid requires additional care as it a little softer than the other varieties and is brittle, meaning that it can chip and scratch more easily.
With its assortment of colours and appearances, there should be a garnet for everybody. Whatever your preference, we can help you to find the perfect stone. Our experienced gemmologists can also answer your questions on this fascinating gemstone family.