Nature has her way of leaving her fingerprints on everything she creates, thereby making everything unique in their own way and value. So when one evaluates a natural gemstone, it is ideal to know the characteristics of each.
Amethyst, part of the quartz family, is highly sensitive to heat and exposing the gem to high temperatures will cause discolouration. The better quality of amethyst are intensely velvet and not streaked but rather evenly distributed. Amethyst with a touch of red violet is more valuable.
Aquamarine, known for preserving marriages and stopping wounds from bleeding, is the result of heating certain green, brown and lighter blue beryl to obtain the deeper sea water blue colour. The inclusions in aquamarines usually occur as hollow tubes which sometimes reflect light.
Emerald’s deep green is caused by chrome and inclusions such as bubbles, cracks, foreign crystals which are not necessarily faults. It is a symbol of immortality and incorruptibility.
Garnet is one of the few gemstones that occurs in many colours. The green garnet known as Tsavorite challenges the emerald for green magnificence. Orange spessartite garnets that were recently found in Africa have been named Malaya garnet. Although the price range of garnets run from a few to thousands of dollars, it is interesting to note that garnets are usually found high on the clarity grades.
Jade is an all-inclusive term for two different and distinct materials – jadeite and nephrite. Jadeite is commonly linked with Chinese artistry and the green translucent material called Imperial Jade. However, jadeite comes in a variety of colours, of which Imperial is only one of the grades. The Imperial Jade derived its name from the Chou dynasty’s (1700 B.C.) Empress Tzu Hsi. During her reign, all Chinese artisans upon completing a piece of work were required to offer it first to the Empress, who would only select a specific grade of translucent apple green jade. In the West, this grade of jade is known as Imperial but in the Orient, it is called “Old Mine”.
The other jade material – nephrite – traces its roots back to the Spanish conquistadores who called the polished pebbles, piedra de tjada (stone of the kidney). It was only in 1863 that the French proved that jade consisted of two minerals.
Unlike nephrite which can be found almost everywhere in the world, jadeite can only be found in Burma and Southern California. The interesting point is that most of the knowledge and understanding of this precious stone still remains in the Orient.
Jade is valued according to the 3T’s – Tone, Translucency and Texture. Tone refers to a specific colour. The finest jadeite colours are described as pure, evenly distributed and free of brown and gray tones. Translucency is the quality which can range from transparent to opaque. The texture of jade can range from fine to coarse and is closely related to its translucency. The highest quality of jade is clear and free of irregularities.
The growing popularity of jade in the Western market coincided with the opening of political relations between China and the Western world and also due to the fact that jade can be easily accessorised and its colour range.
Lapis Lazuli, one of the oldest gemstones, is often known as the stone of royalty. The best quality, Persian Lapis, comes from Afghanistan and mined irregularly in primitive conditions. It has an evenly distributed intense deep blue. Pyrite spots add value and signify genuineness of the gem.
Opal is divided into opalescent precious opals, yellow-red fire opals and common opals. There are two types of precious opals, namely the clear, white or milky opals and black opals. The best precious opals are from Australia. Fire opals, found in Mexico, are mostly reddish or orange and are usually transparent. The advantage of fire opals is that they can be faceted iinto attractive gems but are very sensitive to stress. Common opals are usually opaque and without play of colour. In general, opals are too soft and fragile to make good gems.
Ruby is most valuable when it has a slight touch of violet or pink as a secondary colour. It is less valuable if the purple or violet influences the intense red hue.
Sapphire’s most desired colour is that of a deep, rich blue. Its price fluctuates, as a secondary gray or violet penetrates the colouration.
Topaz occurs in a range of colours such as red-brown, light blue, pinkish red and pale green. The best quality of topaz, known as Imperial topaz is sherry yellow in colour. Coloured topaz is usually emerald- or scissor-cut.
Tourmaline was called aschentrekker by the Dutch in the 1700s as it attracts ash when it is heated. It is a collector’s gem as it is hard, durable and capable of accepting a bright polish. Tourmaline is available in violet, blue-green, brown, yellow, orange, pink, red and black. Its major drawback is a lack of dispersion.
Turquoise has been called the Turkish stone as they were brought to Europe via Turkey. These gems were found in the ancient pyramids of Egypt. The best quality turquoise, Perisan Turquoise, comes from the Nischapur area in northeast Iran. It comes in a pure, dense and even blue colour. The porosity and chemical composition present colour change problems. Heat, exposure to light, perspiration, oils and cosmetics will turn its sky blue colour to green.
Zircon, often used as an imitation diamond, occurs in a variety of colours – yellow, orange, green, blue, brown and red. Blessed with great dispersion and fire, it is brittle and sensitive to hard knocks. Found mostly in gray-brown or red-brown stones, zircon is often heat treated to produce colourless or blue zircons.