Gemology

Properties of Amber

amber-colours

Lustre Amber has resinous lustre. Some softer Dominican amber  is waxy. On exposure to air amber alters due to oxidation, Initially pale osseous amber acquires a thin clear layer like porcelain. Amber generally shows deterioration on surface to such an extent that the rusty-red crust crumbles away exposing a new surface which will undergo the […]

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Information on Amber

amber-stone

Million years ago barks of trees in the forests of some parts of the world began to seep globs of sticky resin. This aromatic resin oozed down the sides of trees, as well as filling internal fissures, trapping debris, such as seeds, leaves, feathers and insects. As geologic time progressed the forests were buried and […]

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Diamond gemstone

diamond-gemstone

Chemical Composition : Carbon C Crystal system: Isotropic or Cubic System Habit : The octahedron and the more complex trisoctahedron and hexoctahedron (form in which the normal octahedral face is replaced by three faces and six triangular faces respectively), rhombic dodecahedron may also occur. Twinned octahedra, known as macles, are common. Whereas the tetrahedron (a […]

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Garnet gemstones

garnet-group-of-gemstones

This is an isomorphous group of minerals which include several species used in jewellery, the most important of which are grossular (tsavorite), grossularite (hessonite), pyrope, almandine, spessartite and andradite with its sub-variety demantoid. GENERAL PROPERTIES OF THE GROUP Chemical Composition : All consists of a double silicate and calcium or magnesium or manganese, aluminium or […]

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Fluorspar

fluorspar-gemstone

Chemical composition: Calcium Fluoride Crystal characteristics: Cubic system. Usually occurs in cubes. Colour: Violet blue, purple, green yellow, pink, brown, blue, etc. Rarely colourless. Massive purple and whitish banded variety known as “Blue John”. Often parti coloured fluorspar is common. Physical properties: Hardness – 4, too soft to retain polish. S.G. – 3.18, R.I. – […]

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Jade gemstone

jade-gemstone

Jade is known as a mineral found out by the Chinese around 1000 BC and prized it above all other gemstones. As a whole jade does not signify one mineral but has two different mineral as variety which does not have any relation in the chemical nature of the gemstones except in appearance. 1. Nephrite, […]

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Lapis lazuli gemstone

lapis-lazuli-gemstone

This stone is characterised by its beautiful colour, which in best specimens is a uniform dark blue of great intensity. Paler tints are common and stones are often mottled. Specimens usually contain brassy spangles of iron pyrites. Characteristics: It is really a rock; a mixture of different minerals (a) hauynite, (b) calcite, (c) sodalite; iron […]

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Opal gemstone

opal-group-of-gemstones

Chemical composition: Hydrous silica di-oxide. Silica with a variable percentage of water (6% to 10%), impurities consisting of the oxides of iron, aluminium, calcium and magnesium are often present. Characteristics: Non-crystalline, amorphous. A solid silica “gel”. Varieties: (a) White opal, (b) black opal, both with play of colours (c) Fire opal, red to orange or […]

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Corundum gemstones

corundum-group-of-gemstones

Chemical Composition : Oxide of aluminium or “alumina”. Crystal System : Trigonal system. The symmetry is trigonal, or threefold, along the vertical axis. Habit: Crystals often appear to possess hexagonal symmetry. Ruby occurs commonly as a hexagonal prism, often with a striations parallel to the rhombohedron edge and with triangular striations or raised triangles on […]

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Chrysoberyl gemstone

chrysoberyl group of gemstones

Chemical Composition : Beryllium aluminate. Crystal Characteristics : Orthorhombic system. Interpenetrant or cyclic twinning is common, giving rise to complicated habits having a hexagonal appearance. Single crystals are rare, but when found have a habit similar to that of peridot. Varieties : Pale lemon-yellow to golden-yellow, brown and green; grass green to brownish-green with colour […]

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Beryl group of gemstones

gemstones that belong to beryl group

Chemical Composition : Silicate of beryllium and aluminium. Crystal Characteristics : Hexagonal system with full hexagonal symmetry. Crystals usually long, prismatic, terminated by a flat face called the basal pinacoid. In other beryls and aquamarines pyramid faces are often present in addition to the basal pinacoid. Emerald crystals are commonly flawed, aquamarine and beryl occurs […]

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Peridot gemstone

image of peridot gemstone

The mineralogical name of this stone is Olivine. Peridot is the green gem variety of Olivine. Chemical composition: Silicate of magnesium and iron. The properties of magnesium and iron vary considerably, giving in effect of an isomorphism series. The colour is due to iron which is part of the basic formula. The mineral is therefore […]

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