Cubic Zirconia
Cubic zirconia or CZ is a synthetic variant of the mineral baddeleyite which is extremely rare in nature. It is the oxide of the metallic element zirconium, zirconium dioxide. It was first used in the Russian space program to serve as a window to photograph through, it was not used in jewellery until 1969 when somebody decided to facet the material. It is often used as a diamond simulant. Cubic zirconia should not be confused with zircon, which is a rare naturally occurring gemstone.
Colour: By adding other minerals in the creative process CZ's can come in any colour as well as the colourless variety.
Hardness:8.25-8.75
N.B. Key features that distinguish CZ from diamond:
Cubic zirconias have more dispersion than diamonds so show more fire.
A CZ has a Mohs rating of 8.5-9 and Diamonds have a rating of 10.
A CZ is 1.7 times heavier than a diamond of equivalent size.
CZs are optically flawless whereas the majority of diamonds have inclusions or flaws
CZ has a refractive index of 2.176, compared to a diamond's 2.417.
CZ can be made in most cases entirely colourless: equivalent to a perfect "D" on diamond's colour grading scale but it is rare to find diamonds are truly colourless.
CZs are thermal insulators whilst diamonds are among the most efficient thermal conductors.
Jade
The term "jade"refers to two different, yet similar semi-precious metamorphic mineral gemstones, Jadeite and Nephrite. Nephrite and jadeite are resistance to breakage and chipping and due to their toughness they made a superior weapons and tools for early man. Not until the 19th century that a French mineralogist determined that "jade" was in fact two different materials. Nephrite is usually only green and creamy white, while jadeite can have the full range of jades colours. Jade is mined in the regions of Canada, Australia, United States and Taiwan.
Hardness:6
Moonstone
Moonstone is the best known gem variety of orthoclase feldspar. It is usually polished as a cabochon. Its importance as a gemstone arises because of adularescence, a floating light effect and sheen, compared to the light of the moon. This phenomena results from alternating layers of two kinds of feldspar,which cause light to scatter. Moonstone specimens commonly exhibit chatoyancy (a mobile, wavering striped reflection), and sometimes display a strong cat's eye.
Colour: most desirable colour of moonstone is blue, but it also occurs in grey, white, pink, green and brown.
Hardness: 6 to 6.5
onyx
Onyx is a chalcedony that occurs in bands of different colours. Onyx refers to a black and white banded variety of Agate and brown varieties are named Sardonyx. It is composed of relatively straight, parallel layers of different colours. This structure lends itself to cameo making.
It is usually cut into cabochon, or into beads, and is also used for intaglios and cameos. Some onyx is natural but much is produced by the staining of agate. It is available in the regions of USA, Germany, Brazil, Mexico, India, and Africa.
Hardness: 7
Quartz
Quartz is a crystalline rock or mineral composed of silicon dioxide. Quartz is the second most common mineral in the Earth's continental crust and found in all types of geological environment. There are 49 variety's, a number of which are gemstones, some of which are very beautiful and very rare. Origin of name from Saxon word Querkluftertz = cross-vein ore.
Colour: colourless, white, gray, yellow to brown to black, violet, pink
Hardness: 7
Topaz
Topaz is a fluorosilicate and can contain trace elements that cause different colours within the Topaz. Origin of name: from Greek Topazion, a Red Sea Island often covered in mist. Topaz wasn't really known about before the classical era, in the Middle Ages the name topaz was used to refer to any yellow gemstone. Deposits of topaz are found in the regions of Russia, Siberia, Brazil, Sri Lanka, Africa and China, Japan, Pakistan, Myanmar, Nigeria, Australia, Mexico, and in the United States.
Colour: Varies in a broad range of: yellow, blue, pink, peach, gold, green, red, and brown.
Hardness: 8
N.B. Topaz is often heated to change or enhance it's colour.
Tigers Eye
Tigers Eye is mainly composed of silicon dioxide, it is a form of quartz that acquires fine golden lustre when polished. Origin of name: the stone resembles the eye of a tiger. Tiger's eye is a semi precious stone with a rich yellow and golden brown stripes that display chattoyance(a mobile, wavering striped reflection). Tigers eye is found in regions of South Africa and Western Australia.
Turquoise
Turquoise is composed of aluminium phosphate and copper. Origin of name: from French for Turkish stone as in ancient days it was transported through Turkey. It was very popular during the days of Ancient Egypt and Ancient Persia and known to man since at least 6,000 BC. Delicate veining, caused by impurities, is desired by some collectors as proof of a natural stone. Turquoise is found in the regions of Iran, southwestern United States, Africa, Australia, Tibet, China, Siberia and Europe.
Colour: Blue, blue-green, green
Hardness: 5-6