Gemstone

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Gem is any mineral that is highly prized for its beauty, durability, and rarity. It is enhanced in some manner by altering its shape, usually by cutting and polishing. Most gems begin as crystals of minerals or as aggregates of crystals. Non-organic origin material (eg pearl, red coral and amber) with several crystal origin is also classified as precious stones.

HISTORY OF GEMS

The use of gemstones in human history goes back to the Upper Paleolithic Period (25,000–12,000 BCE). People were initially drawn by the bright colors and beautiful patterns of gems. When the shaping of stones for adornment first began, opaque and soft specimens were used. As shaping techniques improved, harder stones began to be cut into gems. Beads of the quartz varieties hard carnelian and rock crystal were fashioned in Mesopotamia (now Iraq) in the 7th millennium BCE. Records of the time suggest that people thought that stones had a mystic value—a belief that persists to the present.

GEM MINING

Gemstone deposits form in different geological environments. Perhaps the best known are the “pipes” of kimberlite, from which most diamonds are recovered by the hard-rock methods of drilling and blasting. Other gems also recovered from the rock in which they form are quartz varieties, opal, tourmaline, topaz, emerald, aquamarine, some sapphires and rubies, turquoise, lapis lazuli, and chrysoberyl. Hard and dense gemstones that are impervious to chemical weathering are carried by water to placer deposits such as river beds, beaches, and the ocean floor. Placer mining techniques mimic the creation of the placer by separating denser minerals in running water. The simplest methods are panning and sieving, or passing gravel through a trough of flowing water with baffles at the bottom. The lighter material washes away but denser gemstones remain.

FACETING

Gemstones can be shaped in several ways. Opaque or translucent semiprecious stones, such as agate and jasper, are tumble-polished, carved, engraved, or cut with a rounded upper surface and a flat underside. Grinding and polishing of flat faces on the stone is called faceting. Facets are placed in specific geometric positions at specific angles according to the bending of light within a particular GEM CUTS There are three basic types of facet cut: step (with rectangular facets), brilliant (with triangular facets), and mixed (a combination of the two). The first faceting probably involved diamond cutting in Italy prior to the 15th century. First, only the natural faces of octahedral diamond crystals were polished. stone. Transparent stones, such as amethyst, diamond, and sapphire, are faceted to maximize their brilliance and “fire” or enhance color. Although much material is ground away while cutting, the final value is much enhanced.

GEM CUTS

There are three basic types of facet cut: step (with rectangular facets), brilliant (with triangular facets), and mixed (a combination of the two). The first faceting probably involved diamond cutting in Italy prior to the 15th century. First, only the natural faces of octahedral diamond crystals were polished. stone. Transparent stones, such as amethyst, diamond, and sapphire, are faceted to maximize their brilliance and “fire” or enhance color. Although much material is ground away while cutting, the final value is much enhanced. The rose cut was developed in the 17th century. By about 1700, the brilliant cut (today’s favorite for diamonds and other colorless gems) was created. The emerald cut was soon developed to save valuable material, as its rectangular cut conforms to the shape of emerald crystals. Today there are hundreds of possible gem cuts.

Turquoise

Turquoise-pyrite-quartzTurquoise, Bishop Mine, River Manganese District, Campbell County, Virginia, USATurquoise pebble, made by tumbling the rough rock in a rotating drum...

Chrysoberyl

Chrysoberyl is a member of oxide mineral or gemstone with the formula: BeAl2O4.In spite of the similarity in their names, chrysoberyl and beryl are absolutely extraordinary stones, despite the fact that both include beryllium. Chrysoberyl is the third most commonplace herbal stone and is found at 8.5 at the Mohs

Spodumene

Spodumene is a pyroxene member of inosilicate mineral with chemical formula is LiAl(SiO3)2, lithium aluminium. It can also be pink, lilac, or green. Crystals are prismatic, flattened, and typically striated along their length. Gem varieties of the mineral usually exhibit strong pleochroism.

Beryl

Beryl is a member of cyclosilicate minerals with composed of beryllium aluminium. Chemical formula: Be3Al2Si6O18. Few people have ever heard of the mineral beryl but almost everyone has heard of its principal gemstone varieties emerald and aquamarine.

Opal

Opal from Yowah, Queensland, Australia
Hydrophane opal (precious opal) dried out (Tertiary; Ethiopia)Opal from Yowah, Queensland, Australia Opal is classed a mineraloid, crystalline...

Diamond

The hardest known mineral, diamond is pure carbon. Its crystals typically occur as octahedrons and cubes with rounded edges and slightly convex faces. Crystals may be transparent, translucent, or opaque. They range from colorless to black, with brown and yellow being the most common colors. Other forms include bort or boart (irregular or granular black diamond) and carbonado (microcrystalline masses).

Tourmaline

Tourmaline
"Tourmaline" is the call of a huge group of boron silicate minerals that share a commonplace crystal structure and similar physical residences - but range quite in chemical composition. The huge variety of compositions, in conjunction with trace elements and shade facilities, causes tourmaline to arise in extra colours and shade mixtures than some other mineral institution.

Spinel

Spinel is the name of both an individual mineral and of a group of metal-oxide minerals that share the same crystal structure. Minerals in this group include gahnite, franklinite, and chromite. Spinel is found as glassy, hard octahedra, or as grains or masses.

Quartz

Quartz is one of the most famous minerals on the earth. It occurs in essentially all mineral environments, and is the crucial constituent of many rocks. Quartz is likewise the maximum varied of all minerals, taking place in all distinct bureaucracy, habits, and colorings. There are more range names given to Quartz than any other mineral. Although the Feldspars as a group are more regular than Quartz, as an man or woman mineral Quartz is the maximum commonplace mineral.

Titanite

Titanite, or sphene , which means wedge, is a calcium titanium nesosilicate mineral, CaTiSiO5. Trace impurities of iron and aluminium are generally gift. Also normally present are rare earth metals which includes cerium and yttrium; calcium can be partly replaced by thorium.

Topaz

Topaz is a silicate mineral of aluminium and fluorine with the chemical formula Al2SiO4(F, OH)2. Topaz crystallizes in the orthorhombic system, and its crystals are mostly prismatic terminated by pyramidal and other faces.

Zircon

Zircon is a zirconium silicate mineral with a chemical composition of ZrSiO4. It is common at some point of the world as a minor constituent of igneous, metamorphic, and sedimentary rocks.Zircon is a popular gemstone that has been used for almost 2000 years.