what is gem stone???
To be regarded as a gemstone a mineral(or occasionally an organic material) must be beautiful, most importantly in its color.Five major gem stones
Diamond ......
Diamond is the hardness mineral on earth and this combined with its exceptional lustre and
brilliant fire,has made it the most highly prized of all gems. Pure, colorless diamond is the most popular, But other varieties from yellow and brown to green, blue, pink, red, gray and black-are also found, depending on the impurities present. Because of the uniform arrangement of their constituent carbon atoms, diamond crystal are well formed usually octahedral with rounded edges and slightly convex faces.Their prefect cleavage facilities the early stages of fashioning but they can only be polished by other diamonds.
Star sapphire.....
All gem quality corundum that is not red is called sapphire yet this name is popularly associated with the color blue. Variation in color,due to iron and titanium impurities, spams many shades but most valuable is a clear deep blue. Some stones, called "color change sapphire" exhibit different shades of blue in artificial and natural light.Good quality sapphire is found in Burma,Sri lanka and india.The best indian sapphire is cornflower blue,and found in kashmir,either in pegmatites or as waterworn pebbles in alluvial deposits.
Ruby.....
Ruby-the name given to red,gem quality corundum is one of the best gemstones for jewellery settings. Rubies may be any shade of red,from pinkish to purplish or brownish red,depending on the chromium and iron content of the stone. Frequently twinning of the crystals makes the material liable to fracture,yet ruby is a tough mineral,second only to diamond in hardness.Crystal prisms are hexagonal with tapering or flat ends. As the crystals grow they from new layers, and depending on the geological conditions and minerals present,color variations,called zoning,occur.
Fluorite......
Formerly called fluorspar, fluorite has limited use as a gemstone because it is relatively soft and therefore easily scratched. however the wide range of colors(including yellow,blue,pink,purple and green) the frequent incidence of more than one color is a single specimen and zoning or patchy distribution of color, make in an interesting stone.Despite its fragility and prefect octahedral cleavage stone may be faceted and can be polished very brightly. Cabochons of fluorite have been capped with rock crystal to protect them from scratching.
Ruby-the name given to red,gem quality corundum is one of the best gemstones for jewellery settings. Rubies may be any shade of red,from pinkish to purplish or brownish red,depending on the chromium and iron content of the stone. Frequently twinning of the crystals makes the material liable to fracture,yet ruby is a tough mineral,second only to diamond in hardness.Crystal prisms are hexagonal with tapering or flat ends. As the crystals grow they from new layers, and depending on the geological conditions and minerals present,color variations,called zoning,occur.
What Are The Ruby Treatments?
A treated Ruby is not a bad thing. Less than 1% off all Rubies that are recovered from the ground actually make it to the market without any treatment. These are the most precious and value Rubies available. If they did not treat Ruby gemstones, 99% of the Ruby would never make it to the market. That means the average person may never see a Ruby in their whole life if it was not for treatments.
Untreated Ruby
By far the rarest and most valuable Ruby gemstone. These stones ave been mined out of the ground, cut and polished and presented to the market. No other process apart from cutting and polishing has been performed on these Rubies.
Heat Treated Ruby
This technique has been used for centuries to treat Ruby gemstones. It is used to improve the clarity and colour of Rubies. The Ruby is placed in a crucible and heated to extreme temperatures of around 1800 degrees. The atmosphere around the Ruby can be altered to change the way the Ruby reacts but the basic idea is that the heat will dissolve any rutile inclusions inside the stone which will improve the clarity and improve the red colour. No other additives have been added to the process and the Ruby is as strong and durable as the unheated version.
Fluorite......
Formerly called fluorspar, fluorite has limited use as a gemstone because it is relatively soft and therefore easily scratched. however the wide range of colors(including yellow,blue,pink,purple and green) the frequent incidence of more than one color is a single specimen and zoning or patchy distribution of color, make in an interesting stone.Despite its fragility and prefect octahedral cleavage stone may be faceted and can be polished very brightly. Cabochons of fluorite have been capped with rock crystal to protect them from scratching.
Pyrope(Garnet).......
The blood - red color of pyrope is due to its iron and chromium content.It rarely has inclusions,but when present they are rounded crystals or having irregular outlines. As with garnets pyrope has no cleavage and fracture is to uneven.But when present they arerounded outlines.
Spessartine(Garnet).......
Gem-quality spessartine is uncommon. It is bright orange when pure, but an increase in the iron content makes the stone darker orange to red. Inclusions are lace- or feather-like.
*OCCURRENCE Spessartine occurs in granitic pegmatites and alluvial deposits. It is found in Sri Lanka, Madagascar, Brazil, Sweden, Australia, Burma, and the USA; also Germany and Italy, but crystals there are too small to facet.
• REMARK Spessartine is named after the Spessart district of Bavaria, Germany. It can be confused with hessonite garnet or yellow topaz, but on close examination of inclusions it is distinguishable
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. It is one of the hardest naturally occurring minerals (Mohs hardness of 8) and is the hardest of any silicate mineral. This hardness combined with its usual transparency and variety of colors means that it has acquired wide use in jewellery as a cut gemstone as well as for intaglios and other gemstone carvings.
