Beryl

Varieties

Beryl exists in a number of different varieties, some being better known by their own name, for example, emerald is the grass green variety and aquamarine is the sky blue variety.

Colouration

Pure beryl is colourless, often called white, and although quite rare, tends not to be valuable because it does not have much brilliance. Colours, as in many gemstones, are caused by small amounts of impurity, usually metallic oxides. This is another case where impurity is desirable.Chromium, in the form of chromic oxide, causes the bright grassy green colouring in beryl, thereby producing beryls.Vanadium can also affect the exact shade, as may traces of iron.It is also possible to have green beryl which is not emerald, because the colouring agent is not chromium.

Hardness

Beryl is quite hard, having a hardness of 71/2 to 8 on Moh's scale, compared with 10 for diamond, 9 for corundum, and 8 for topaz. Hardness is generally a desirable feature is gemstones.

Cleaning

Beryl jewellery can be carefully cleaned using warm soapy water, or detergent, rinse thoroughly afterwards as detergents can cause dermatitis and allergic reactions. Enzyme cleaners should be avoided for the same reasons. Brushing with an old tooth brush to remove dirt and grease will also help. Cleaning agents containing chlorine may have a detrimental effect on low carat gold alloys, so are best avoided.We stress that reasonable care should be taken when cleaning emeralds, as washing with strong detergents could cause any oil to be diluted or removed, requiring the stone to be re-oiled.Beryls do not like excessive heat, and although they can tolerate temperatures above 100c (the boiling point of water), it is advisable to use warm water rather than hot water, to reduce the dangers of thermal shock.It is not advisable to clean beryl in an ultrasonic tank. We sometimes risk it with our own stock, but we would never clean a large or valuable beryl which did not belong to us, in an ultrasonic machine.