Turquoise is a form of copper aluminium phosphate ranging in colour from blue to yellowish green. It is the most valuable of the opaque stones with intense blue being the most prized colour.

Turquoise is a symbol of courage and success. It was believed to protect from poison and to change colour as a warning of impending death. Buddha is said to have destroyed a monster using turquoise.

Turquoise can be easily scratched and is porous and, so, should not be brought into contact oil or dirty or soapy water.
 

Topaz is a clear, crystalline form of aluminium and fluorine silicate. It exists in a variety of colours including white, yellow, yellow-brown, orange, light red, light blue, light green and (rarely) violet.

Topaz is a symbol of love and affection and was believed to aid sweetness of disposition.

Many stones sold as topaz are in fact citrine, which is lighter than topaz. (True topaz is far more expensive than citrine.)

Yellow and blue topaz may fade after long exposure to light.
 

Sapphire is the blue form of corundum. Yellow, pink and green forms of the gem, know as "fancy sapphires" also exist. The finest sapphires have a brilliant, deep, velvety blue colour. Like the star ruby, the star sapphire is a translucent variety which produces a six-pointed star effect when cut as a cabochon (dome).

Sapphire is the symbol of the heavens and was believed to bestow innocence and chastity.
 

Ruby is the red form of corundum. It ranges in colour from bluish red to yellowish red. The finest rubies are a vivid, pure red with a faint hint of blue. The star ruby is a translucent variety which produces a six-pointed star effect when cut as a cabochon (dome).

Ruby is the symbol of love and passion and was was believed to ensure true friendship.

Because the ruby is such a prized stone, synthetic versions have been produced; some of these are very close to natural rubies.
 

Peridot is a brown or greenish-yellow form of chrysolite. Peridot may be transparent or translucent and has an exceptionally rich colour.

Peridot was believed to free the wearer of envy and to aid friendship, to cure diseases of the liver and, if worn on the left arm, to give protection from the evil eye.

Peridot can easily be scratched.
 

Opal is a form of silicon dioxide in which many colours, caused by reflections from microcrystalline silica spheres, may be seen when it is turned in the light. Opal is divided into two types - black or white - according to the background colour of the stone. It’s value is determined by the brilliance of the colour, the absence of dead spots and flawlessness. Black opal is considered the finest and those with an abundance of red are the most valuable. Opals which are strong in green and blue are not as rare.

Opal was thought to be a bad omen yet to be a symbol of fidelity and to have the ability to cure diseases of the eye.

Opals tend to dry and crack and benefit from an occasional coating with olive oil.
 

Onyx is a banded, semi-translucent or opaque form of quartz. It occurs in a variety of shades of red, orange, apricot and brown with bands of white. Red and white banded onyx is called sardonyx; grey and white onyx is called chalcedony.

Onyx was believed to create disharmony, bring bad dreams and broken sleep and to be a bad omen for lovers.
 

Lapis lazuli is a composite mineral which has an intense, brilliant, deep blue colour. It sometimes contains gold or silver coloured flecks which are pyrites (fools’ gold). The finest quality lapis lazuli has a deep, even blue with no flecks.

Lapis was associated with capacity, brilliance, success and divine favour. When worked in the form of an eye and ornamented with gold it was thought to posses great power.
 

Garnet is a crystalline silicate. Although the best known colour of garnets is red, they can be found in almost every colour except blue. Green garnet is similar in appearance to emerald but more brilliant and more durable. Red garnet can be confused with ruby and yellow garnet can look like topaz. There is also a non-transparent variety which looks like jade.

Garnet were believed to promote sincerity and stop anger and discord. A garnet with a lion carved on it would preserve honour and health, cure all diseases and guard the wearer from the perils of travel.
 

Emerald is the green form of beryl. The finest emerald has the colour of green grass with a very faint hint of blue. Flawless emeralds are very rare. Since early Greek times, emeralds have been boiled in oil. This hides some of the flaws, which are actually tiny cracks, because they become filled with oil and more difficult to see.

Emerald was believed to bring faithfulness and to give the ability to predict the future.

Because emeralds are valuable, imitation emeralds are often made by inserting layers of green glass, or a green cement, between pieces of aquamarine or quartz. The resulting stone has almost identical physical and optical properties to emerald.
 

Coral is a semitransparent to opaque form of calcium carbonate. It occurs in a variety of colours including white, pink, orange and black. The rarest, and most expensive, variety is blood coral which has a deep red colour. Another valued variety is called "angel skin"; this is white in colour with a faint tinge of pink or peach.

It was believed that coral could cure madness, give wisdom, stop bleeding, calm storms and prevent sterility. To retain its powers it had to be kept uncut.

Coral is usually cabochon cut (i.e. dome shaped), or carved. It will be damaged by contact with any acid, including vinegar.
 

Carnelian is a form of quartz which is usually reddish orange, although it can range from orange to ruby red. It varies from opaque to brilliantly transparent.

Carnelian was believed to give courage to speak boldly and well. It is particularly revered by Moslems because Mohamed wore a silver ring set with a carnelian.

Carnelian was often used in jewellery, especially cameos, and was also widely used for seals because wax does not stick to it.
 

Bloodstone, or heliotrope, is a variety of quartz. It is dark green in colour with specks of red throughout. The most valuable bloodstone is less dark with pronounced, round red flecks.

Bloodstone was believed to stop bleeding, cure snakebites, prevent sunstroke and headache and protect the wearer from the evil eye.
 

Amethyst is a translucent purple variety of quartz. It is often streaked and heat of strong light will cause fading.

Amethyst was believed to prevent drunkenness and to bring peace of mind. If the sun or moon was engraved on an amethyst, it was believed to prevent death by poison.
 

Amber is a wonderful substance that has been popular since the dawn of time. Is is a resin which came from prehistoric coniferous trees and is now found around the world in deposits dating back 85 to 100 million years.

The largest known deposits of amber are from the Baltic Sea in Europe.

Amber varies in colour and may be yellow, yellow-brown or deep orange. It often holds the remains of fossilised insects and pollen.

Amber has been valued by many cultures and reference to it appears in the mythology of the East and West.

Amulets and beads of amber, dating back to 10,000 BC have been found in England. Carved amber was traded by the Etruscans as far back as the 5th Century BC. In Asia, the oldest amber carvings were mainly done with amber from Burma.
 

Agate is formed when silica gel dries and hardens over a long period of time into a form of quartz, coloured by impurities. Agate is usually found in pastel colours but almost any colour or pattern is possible. Patterns include banded agate, moss agate which is white with what looks like a black, brown or green moss growing within it, plume agate which look like it contains plumes of feathers and eye agate which has an eyeball effect.

It was believed to give wearers a bold heart and protect then from dangers. It could cure insomnia and ensure good dreams. In the 19th century eye agate was believed to take on the watchfulness of a guardian spirit and protect the wearer from evil. As such, it commanded very prices.