
Sapphire Formation
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How are sapphires formed?
The word Sapphire has the Greek roots sapphire which means blue. These are blue gemstones that are used in jewelry and decorative products. The blue color sapphires are considered the most valuable. Sapphires have other colors pink, golden, white, and black. Another distinctive factor in sapphire stone is that has a rutile which is an ore form of titanium that reflects light and forms a six-pointed star. It is also known as star sapphire. All the translucent forms of mineral are sapphires. The high-quality sapphires are located in a few places including southern Asia and eastern Africa and the islands of Sri Lanka (Ceylon) and Madagascar.
Mostly sapphires are formed in depths of 6–18 miles on the earth's surface. The intense mounted high pressure along with high temperatures which is above 800 degrees. Some of the examples are siltstones and shale. Sapphires are mostly extracted from different types of rocks granite, schist, gneiss, nepheline syenite, and other forms of rocks that naturally occur on Earth's surface. Sapphires are hexagonal in structure. The hardness of sapphires is similar to diamonds and is considered the second most valuable gemstone after diamond. The price of sapphires is higher than other types of gemstones and minerals.
Colors of Sapphire
Sapphires' different colors are based on the different mineral combination that causes changes in the colors of sapphire. The most common variety of colors in sapphires is pink, yellow, and the most known blue. The sapphires that have iron traces usually form a yellow color.
Blue Sapphire
The pure types of sapphires are formed as a result of changes in igneous rocks. The magma cooling is directly linked to the size of sapphire. When magma cools down slowly it forms bigger sapphires. Similarly, if the magma takes a long time to cool down it forms small sapphires. The formation of larger sapphires is rare in nature. The sapphire reserves in the earth are usually in the form of a barrel shape which is longer and larger in the center.
Crystallization
The crystallization occurs in two steps in sapphire which are the nucleus phase and the inclusions of other layers in sapphire crystal. In the nucleus phase initial structure of the sapphire is formed defines the shape of the sapphire. The second phase is the inclusion phase in which other layers of sapphire are formed. Sapphires have hexagonal bi-pyramids in their structure. Sometimes rutile is formed which is out growth of sapphire during the formation. Natural sapphires are heated to improve their color.
Tone
The tone is linked to lightness or darkness within a sapphire. The two sapphires can have the same color but different tones. For example, a sapphire can have a light blue tone and another sapphire can have a deep blue in its tone. Both sapphires are the same in color but there is a difference in their tones.
Saturation
Saturation is called the intensity of a sapphire's color. Sapphires that have higher saturations are pure in color with no impurities and also known as "vivid" stones. The saturation in sapphires can be strong, medium, fair, and weak. The saturation has a strong influence on sapphire's value. The strong to vivid saturation in sapphires increases the value and worth of gem stone.
Chemical formula of sapphires
In gemology sapphires are the only mineral that has a uniform chemical formula and a three-dimensional structure. The chemical formula of sapphire is Al2O3 which is Aluminum oxide.
Millions of years ago the rocks inside the earth's crust underwent high pressures and high temperatures. The changes in the earth's crust temperature change the composition of atoms. The atoms change their bonds with new types of metamorphic rocks that include rubies and sapphires. The sapphire stone deposits are also located in Kashmir, Burma, and Sri Lanka. For example, blue sapphires have traces of other mineral inclusions that form distinctive patterns of silk which helps geologists to figure out the accurate geographic location within the earth's crust.