Semi-Precious Gems Explained

AMETHYST
A transparent variety of crystalline quartz, amethyst ranges in colour from very pale mauve to deep purple. Versatile and distinctive, amethyst was used by ancient Romans and Greeks for intaglio seal stones and was favoured by Church for bishops' rings and pectoral crosses. The finest stones originated from Siberia although the majority of amethyst used in 19th century jewelry were from Brazil and Uruguay.

AQUAMARINE
The pale transparent blue variety of beryl, aquamarine originate from Brazil where fairly massive crystals have been discovered. Aquamarine is often confused with blue topaz and synthetic blue spinel and it is recommended that pieces made after the 1950s are tested for authenticity.

CITRINE
A variety of crystalline quartz ranging in colour from the palest lemon through orange and brown, citrine has been used extensively in 19th and 20th century jewelry and ornamentation due to its abundance and modest value.The stone is often confused with topaz, but citrine lacks the brilliance of topaz and, when examined under a magnifying lens, often exhibits varying patches of colour.

GARNET
Once upon a time garnet jewelry was abundant and modestly priced, but recent prices for good antique pieces have resulted in a rapid and justifiable reassessment of their status. Garnet is found in several colours although red is by far the most common.

MOONSTONE
A variety of feldspar, moonstone is appropriately named as it displays a bluish-white sheen effect known as adularescence. Moonstone is practically always polished en cabochon to exhibit its unique lustre. When cut into figurative designs, such as the head of an Egyptian Pharoah or a "man in the moon", the value increases sharply.

OPAL
Milky opals were commonly used in late 19th century jewelry when their sheer versatility resulted in a wide assortment of designs such as bangles, cluster rings, fringe necklaces and crescent brooches. Superior examples exhibit an attractive play of red, green and blue colours whilst inferior milky opals are almost completely white with minimal flashes.

PERIDOT
Formerly known as olivine, peridot is routinely confused with chrysolite, the yellowish green variety of chrysoberyl. The finest peridots are a deep lime-green colour and originated from the island of St. John in the Red Sea. The stone has been set in jewelry since the time of the Romans. Peridots can be identified by their characteristic "doubling of the back facets" when viewed under a magnifying lens: modern examples are often rather pale and insipid.

TOPAZ
A beautiful transparent gemstone of which the three best known colours are golden brown, pink and blue.The finest topaz originated in Brazil and examples of good size and colour are extremely expensive today. Topaz has a characteristic "greasy" or slippery feel quite unlike stones of similar colour such as citrine or zircon.

TOURMALINE
A multi-coloured gemstone of which the two most popular shades are deep green and deep pink. As with several semi-precious gemstones, tourmaline gained widespread popularity at the end of the 19th century in gold pendants, necklaces and brooches.

TURQUOISE
A prominent gemstone from the 18th century onwards, turquoise is well known for its opaque, waxy lustre and unique sky blue colour. The best examples originated in Persia and Egypt. Today, turquoise matrix is produced in large and irregular shape pebble-like forms used in Navajo Indian and New Mexican jewelry.

ZIRCON
The majority of zircons are brownish-green, orange, blue or colourless. The availability of the gemstone after Second World War led to many large three-dimensional brooches and bracelets being made with combination of several different shades of orange and brown. Ziricon exhibits a natural fire and brilliance which has often resulted in colourless zircon being sold as diamond.