SAPPHIRE MINING
DESCRIPTION :
Sapphire is the most precious and valuable blue gemstone. It is a very desirable gemstone due to its excellent color, hardness, durability, and luster. In the gem trade, Sapphire without any color prefix refers to the blue variety of the mineral Corundum. However, the term Sapphire describes all other gem varieties and colors of Corundum as well, excluding Ruby.
* SAPPHIRE - ORIGIN AND SOURCES
HOW DO SAPPHIRES FORM ?
Sapphire is the name for the mineral corundum when it is blue in color. Minerals are composed of atoms of certain elements in certain arrangements. Corundum is made of aluminum and oxygen, and can be blue when the element titanium is incorporated into its atomic structure. Therefore sapphire forms in coarse grained igneous rocks that do not have silica. Coarse grained igneous rocks are formed when molten rock cools slowly under the surface of the earth. Slow cooling allows large crystals of minerals to grow. So the slower the magma cools, the larger the sapphire that forms. Sapphires are formed by the different shifts, mixings and chemical changes that are constantly taking place in the earth. Sapphires are created through certain shifts in heat and pressure, and can be found in both metamorphic and igneous rocks. Rocks in which sapphires can be found include granite, schist, gneiss, nephaline, syenite and a variety of others. They may also be found in deposits of alluvium. When sapphires are formed naturally, they are hexagonal, and are called corundum. Due to the remarkable hardness of sapphires, they are highly prized.
ARTIFICIAL SAPPHIRES :
With advances in science and technology, methods have been created for artificially growing sapphire crystals. The original process was discovered in 1902, and it consisted of alumina powder being added to a oxyhydrogen flame, which is in turn directed downward. A variety of chemicals can be added throughout this process to create sapphires of multiple complexion. While other processes have been discovered since the early 1900's, it is these artificial sapphires that have opened up the use of the stone for technological purposes, including use in panes of glass, and as focusing devices in lasers.
HOW SAPPHIRES ARE MINED ?
Today there are 3 main ways in which sapphires are mined, open mines or shallow pit mines which you will find in countries like Sri Lanka and Madagascar.There are larger commercial mines in countries like Australia and Thailand where large deposits of conundrum (sapphire's) are found both gem quality and commercial grade, these mines can be vast in size and depth. Finally one of the worst type of mining which is being used in south America today as well as some countries in Africa is high water pressure mining. This type of mining trips away the top soil followed by the gem bearing rocks and gravel beds leaving the land bear and desolate. This type of mining can yield high quantities of rough gem stones but permanently destroys the land and has become the most destructive form on mining. Sapphire is of volcanic origin and occurs in alluvial deposits, which are up to 20 meters below the surface. Throughout the ages, sapphires and other heavy minerals were transported and deposited in layers and thus tend to be concentrated in 'runs' along particular channels.
MINING PROCESS OF SAPPHIRE :
The most important sources for sapphire are Burma, Kashmir, Sri Lanka, Madagascar, Thailand and Australia. A major source of sapphire is Queensland in Australia's northeast Sapphire fields in the Queensland area use various methods for the mining of sapphires, depending on the depth at which they are found and the weight and hardness of the surrounding materials. In some places simple hand mining methods may be suitable for working surface and shallow wash deposits. Deeper ground is mined by digging shafts, while some fields consist of large-scale open-cut mining lease operations involving the use of heavy earth excavation equipment.
Depending on the type of material surrounding the mined sapphires, processing the mined material in order to collect the sapphires can vary from rudimentary hand sieving and cleaning, to more sophisticated mechanized methods. A typical production method for a shaft mine involves first digging out the mine walls with a jackhammer to loosen the ground. The material is then transported by wheelbarrow to a large drum placed at the bottom of the shaft. Once full, the drum is pulled up via a motorized winch known as the "up and over," and taken to the sapphire processing machinery.
A conveyor belt then carries the sapphire bearing wash into a turning "trommel" which is made of layers of fine and coarse mesh. This sorts out the particles that are too fine as well as the larger sized rocks, called "overburden". The fine sand is discarded while the large rocks are set aside for a quick check to make sure there is not a large sapphire amongst them.
The medium sized wash drops into a pulsater that has eight trays with running water flowing through it. Sapphires are very heavy, so they will remain where they are dropped; the lighter rocks are moved along by the pulsater then dropped onto a tray for removal to the waste pile.
At the end of the day the "sapphire trap" is sorted in order to find the heavy sapphire and zircon, and finally, the best stones are selected to surface into cut gems.
SAPPHIRE TREATMENT :
* Cutting and Polishing :
The cut and polish on a sapphire, or any gem stone, is extremely important .Sapphires are unique in the fact that the stone has an almost unlimited choice of cuts.
Many gem stones are limited to the cuts they can have, depending on the natural make-up of the stone. Sapphires crystals are formed as a hexagon shape. This not only allows for a much more diverse set of cuts, but also explains in part why these beautiful gem stones are so durable. The polish of a sapphire is equally important. The polishing of sapphire is generally poor.
* Heat Treatment :
Heat treatment is an integral part of the sapphire trade. In fact, the practice is so widespread that sapphires that are indicated not to have been heat treated are questioned. The use of heat treatment has been responsible for many of the lower-quality sapphires being sold for higher prices than would otherwise be possible. Many of the New England sapphires possess a characteristic trait, which decreases their value, in the form of needle-like rutile (TiO2) precipitates, commonly known as silk.
Heat treatment involves two aspects of enhancement, these being colour modification and clarity improvement. Both shortcomings can be improved concurrently by high-temperature (~1600?C) reduction. The blue colour can be intensified and homogenized by reduction of Fe3+, solution of Ti4+, and the associated charge-transfer. The clarity is improved by reduction of the TiO2 to Ti2O3, the latter of which is more soluble in the Al2O3 lattice. The relevant reaction is :
SAPPHIRE - ORIGIN AND SOURCES :
Sapphire is found in only a few locations in the world. The three most famous regions for blue sapphire are Kashmir, Burma and Sri Lanka. Sapphire has also been mined in Cambodia, Thailand, Vietnam and India. As of 2007, Madagascar has been leading the world in sapphire production, though Sri Lanka continues to be the only steady producer of fine quality blue sapphire. Sri Lanka and Madagascar produce sapphires in a wide range of colors and while Sri Lanka has been a known sapphire source for centuries, sapphire deposits in Madagascar were only recently discovered in 1998. Today, Madagascar and Tanzania are considered to be two of the most important sapphire sources. Australia is also known for significant sapphire deposits, though most Australian sapphire is known to form rather dark in color. In the USA, there are small sapphire deposits found throughout Montana and North Carolina.
The finest quality blue sapphire, comes from Kashmir and Mogok, Burma. The finest Kashmir and Burmese sapphires display superb color and clarity without any thermal (heat) treatment. Some Sri Lankan (Ceylonese) sapphires are also unheated, but nowadays, the majority of sapphires have been heated, diffused or fracture-filled to improve color and clarity, regardless of their origin. The rare, fine blue sapphires of Pailin, Cambodia were also very highly regarded by gem traders throughout the world. Pailin sapphires ranged in color from light to deep blue, but they possessed a distinctive purity and intensity of color that was unlike any other sapphire sources. Almost all the sapphires from around the world are cut and processed in Chanthaburi, Thailand. Along with Kanchanaburi and Trat, Chanthaburi was once one of main sources for Thai sapphire. There is also a large market for Thai star sapphires that exhibit distinctive golden six-rayed stars. The golden black star sapphire is found nowhere else in the world. Nowadays, Chanthaburi, Thailand has become the main processing and trading center for almost all of the world's sapphires, rubies and other colored gemstones.
PRODUCTIONAL STATISTICS :
USES :
* A symbol of integrity, effective for the efficient resolution of legal matters.
* The sapphire is effective for channeling healing powers from a higher source into the healer.
* A stone of love, fidelity, and commitment; commonly used in engagement rings.
* Used as a professional support stone, keeps the mind stimulated for executives and writers, promotes awareness of higher principles for historians and researchers, and supports good judgement for lawyers and journalists.
* A symbol of wise and honest leadership.
* The sapphire has been used for centuries, most commonly to provide mental acuity and to promote good health.
DESCRIPTION
What is Sapphire?
Sapphire, derivative from the Greek term "sapphirus", factually means blue. Sapphire is a gem stone whose physical and chemical properties are same as the ruby. With two pyramidal features in the hexagonal system it has been crystallized. It is partially stronger and harder than ruby. Inquisitively, all corundum's which are not rubies are grouped as sapphires, which tells that this meticulous gem is available in many colors like blue, green, pink, mauve, white, grey, violet, yellow and orange.
Where Do They Form?
Sapphires form in feldspathoid- posture igneous rocks beneath drenched with deference to silica. They are capable of also forming into recrystallized mineral and high-grade metamorphic rock that is deprived in silica and affluent in aluminum. This comprises marbles and mica schist's.
Composition of Sappire:
- Chemical Composition: AL2O3 + Fe
- Hardness: It is considered "9" on the Mohs' scale of
- Refractive Index: 1.762-1.77
- Pleochroism:Strong dichroism
- Density Around: 4
- Birefringence: 0.008
- O-isotope composition: between 4.4 and 13.9%
Color:
There is dissimilarity in cost among sapphires which depends on the color quality, carat size, shine and brilliance. Despite the fact that the most accepted color is blue and pink the preference of color is an individual choice and with sapphire you can discover them in a lot of colors.
Cut:
The most excellent sapphire cuts proffer a depth/width ratio superior than similar diamond cuts. Expect a deepness percentage of 65% to 80% for high-quality. Deep-cut stones as well conserve weight, raising the price of the stone with no predictable raise in the dimension of the circlet.
Clarity:
Blue sapphires have a tendency to have additional insertion than a good number of fancy color sapphires. Gemologists use the expression "inclusion" to describe uniqueness establish within a stone. Inclusion is frequently used as a sign that the gemstone is of natural origin.
Carat:
Gemstones differ in thickness, so a sapphire and a diamond of the similar carat weight are visually diverse dimensions. As sapphires are likely to be heavier, a one carat sapphire is in general to some extent lesser in size than that of a one carat diamond. The typical size for a round sapphire is 6 mm, which is about one carat.
Natural Occurrence :
Best quality is found in Kashmir (India), Pakistan. It is also found in Burma, Australia (Anakie), Sri Lanka, Thailand(Kanchanaburi), Cambodia(Pailin), Tanzania, Finnish Lapland, South India, Northwest Kenya and USA (Montana, Yogo Gulch). .
Available Colors :
Sapphire is available of blue color shad, referring to the gem of the same name. Sapphire gems are most commonly found in a range of blue shades. In modern usage, 'sapphire' refers to a deep vibrant blue. Sapphire blue is the official balloon color of the Korean boy band, Super Junior.
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