Topaz
stones with a medium reddish-orange with some brown have been called 'Imperial topaz'and are characteristic of some Brazilian deposits. Sherry-brown and pale brown stones may fade, though not all do.
Ruby
the preferred colour is traditionally known as 'pigeon's blood' and is a rich red with a hint of purple. Orange- and brown-tinted reds, characteristic of the rubies from Thailand, still known in the trade…
Opal
black opals command the highest prices and should have as dark a background as possible with maximum variety and intensity of colours.The matrix should be translucent. Red is always a desirable colour. If possible…
Emerald
the preferred colour is an intense bluish-green but it is fair to say that many also like a yellower green which is much brighter.Siberian emeralds are bright and the term is sometimes…
Citrine
the best stones are a rich yellow with orange overtones and range from brown to an orange red. Rio Grande and Madeira are terms used for heat-treated amethyst which has…
Cat’s-eye chrysoberyl
the eye should be silvery-white and very sharp, seen against a background of translucent honey yellow or brown. Some prefer a greenish brown but olive greens are less desirable.
Blue Sapphire
a rich somewhat violet-blue is preferred, a colour which may appear violet-blue in daylight and purplish-blue under tungsten light. This colour is especially characteristic of the finest Burmese stones. Kashmir…
Aquamarine
although most aquamarine is mined as sea-green crystals which give their name to the variety, most aquamarine on the market is a medium blue with no hint of green. This…
Amethyst
a rich purple with a change of colour from reddish-purple under tungsten light to bluish-violet in daylight fetches the highest prices and is known as Siberian. The names Uruguay and…
Alexandrite
the best stones from the Ural Mountains show emerald-green in daylight and rich purple under tungsten light. This combination is extremely rare. Sri Lanka alexandrite has a less pronounced colour…
