Opal is known for its unique display of flashing rainbow colours called play-of-colour.

Tourmalines have one of the widest colour ranges of any gem species, occurring in various shades of virtually every hue.

Rose gold is made by alloying pure gold with copper and silver.

White gold is made by alloying pure gold with white metals such as nickel, silver and palladium. Usually with a rhodium coating.

Smoky quartz is a colour-variety of crystalline quartz.

Platinum is usually mixed with other similar metals such a palladium group metals (palladium, iridium, ruthenium, rhodium and osmium).

Silver is made by alloying pure silver with copper to make it stronger usually known as sterling silver.

Rock crystal, transparent variety of the silica mineral quartz that is valued for its clarity and total lack of colour or flaws.

A brilliant-cut diamond indicates exactly 58 facets to allow maximum light refelction, and characterised by a round outline.

9ct gold is 37.5% pure gold with 62.5% alloying metals. When stamped or hallmarked you will see 9KT or 375.

Emerald cut stones are either rectangular or square cut stones.

Two different gem materials can correctly be called jade. Jadeite is one of them, and the other is nephrite. Both are actually metamorphic rocks made up of tiny interlocking mineral crystals.

Lemon quartz is created by heating amethyst, yellow quartz and iron together at extremely high temperatures.

Rhodium is a precious metal that is in the family of platinum.

Old-cut diamonds are antique and have been cut without the precision of modern technology.

Spinel, like garnet and diamond, is singly refractive, with the same physical properties in all crystal directions.

The radiant-cut diamond combines a rectangular or square cut with cut corners.

Enamel in jewellery and decorative work goes by a few names—vitreous enamel, porcelain enamel, and painted glass.

Tanzanite is the violet blue to blue violet variety of the mineral zoisite.

The cushion-cut diamond combines a square cut with rounded corners.