Portal:Gemology and jewelry

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Introduction

A selection of gemstone pebbles made by tumbling rough rock with abrasive grit in a rotating drum. The biggest pebble here is 40 millimetres (1.6 in) long.

Gemology or gemmology is the science dealing with natural and artificial gemstone materials. It is considered a geoscience and a branch of mineralogy. Some jewelers are academically trained gemologists and are qualified to identify and evaluate gems. Read more...

Amber pendants

Jewellery (British English) or jewelry (American English) consists of small decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes, and the term is restricted to durable ornaments, excluding flowers for example. For many centuries metal, often combined with gemstones, has been the normal material for jewellery, but other materials such as shells and other plant materials may be used. It is one of the oldest type of archaeological artefact – with 100,000-year-old beads made from Nassarius shells thought to be the oldest known jewellery. The basic forms of jewellery vary between cultures but are often extremely long-lived; in European cultures the most common forms of jewellery listed above have persisted since ancient times, while other forms such as adornments for the nose or ankle, important in other cultures, are much less common. Jewellery may be made from a wide range of materials. Gemstones and similar materials such as amber and coral, precious metals, beads, and shells have been widely used, and enamel has often been important. In most cultures jewellery can be understood as a status symbol, for its material properties, its patterns, or for meaningful symbols. Jewellery has been made to adorn nearly every body part, from hairpins to toe rings, and even genital jewellery. The patterns of wearing jewellery between the sexes, and by children and older people can vary greatly between cultures, but adult women have been the most consistent wearers of jewellery; in modern European culture the amount worn by adult males is relatively low compared with other cultures and other periods in European culture. Read more...

Selected article

Opal veins.jpg

The mineraloid opal is amorphous SiO2·nH2O; hydrated silicon dioxide, the water content sometimes being as high as 20% but is usually between three and ten percent. Opal ranges from colorless through white, milky blue, gray, red, yellow, green, brown and black. Common opal is truly amorphous, but precious opal does have a structural element. The word opal comes from the Sanskrit upala, the Greek opallios, and the Latin opalus, meaning "precious stone." Opals are also Australia's National gemstone.

Opal is a mineraloid gel which is deposited at relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, and basalt. Opal is one of the mineraloids that can form or replace fossils. The resulting fossils, though not of any extra scientific interest, appeal to collectors.

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