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 encompasses all other gem varieties and colors of Corundum as well.
Trace amounts of other elements such as iron, titanium, or chromium can give corundum blue, yellow, pink, purple, orange, or greenish color. Chromium impurities in corundum yield a red tint, and the resultant gemstone is called a ruby.
Photo: Logan sapphire with diamonds, National Museum of Natural History, Washington DC
Corundum: Corundum is best known for its gem varieties, Ruby and Sapphire. Ruby and Sapphire are scientifically the same mineral but just different colors. Ruby is the red variety, and Sapphire is the variety that encompasses all other colors, although the most popular and valued color of Sapphire is blue. Sapphire is also only used to describe the gem variety, otherwise it is simply called Corundum. Corundum is a very hard, tough, and stable mineral. For all practical purposes, it is the hardest mineral after Diamond, making it the second hardest mineral. It is also unaffected by acids and most environments.
Crystal structure of corundum, by NIMSoffice at en.wikipedia
The most valuable color of Sapphire is a cornflower blue color, known as Kashmir Sapphire or Cornflower Blue Sapphire. Another extremely valuable Sapphire form is the very rare, orange-pink Padparadschah. An exotic type of sapphire, known as Color Changing Sapphire, displays a different color depending on its lighting. In natural light, Color Changing Sapphire is blue, but in artificial light, it is violet. (This effect is the same phenomenon well-known in the gemstone Alexandrite). Yellow and pink Sapphire have recently become very popular, and are now often seen in jewelry.
Because of the remarkable hardness of sapphires (and of aluminum oxide in general), sapphires are used in some non-ornamental applications, including infrared optical components, such as in scientific instruments; high-durability windows (also used in scientific instruments); wristwatch crystals and movement bearings; and very thin electronic wafers, which are used as the insulating substrates of very special-purpose solid-state electronics (most of which are integrated circuits).
Sapphire was first synthesized in 1902. The process of creating synthetic Sapphire is known as the Verneuil process. Only experts can distinguish between natural and synthetic Sapphire.
Types of sapphires:
Color-Change Sapphire exhibits a different color in natural and artificial light.
Cornflower Blue Sapphire: sapphire with a cornflower-blue color, which can be better described as an intense, velvety-blue color. This term is often used in conjunction with Kashmir Sapphire to describe the Sapphire of that region, but it can also be used to describe any Sapphire with such color.
Cornflower blue is the most desirable color in a Sapphire.
Fancy Sapphire - Describing any Sapphire with a color other than blue.
Kashmir Sapphire: has an intense, velvety-blue color, described from the Kashmir Province of India. Kashmir Sapphire is considered to have the finest color of all Sapphire.
Padparadschah: Orange-pink variety of Sapphire that is found in Sri Lanka; highly regarded and one of the most valuable forms of Sapphire.
Star Sapphire: a form of Sapphire displaying asterism in the form of a distinct, six-rayed star.
False names:
You can also encounter gemstones that are called sapphire, but are not in fact sapphires.
Brazilian Sapphire - Blue Tourmaline or Blue Topaz
Gold Sapphire - Lapis Lazuli with shiny Pyrite sprinkles
Hope Sapphire - Synthetic Blue Spinel
Lux Sapphire - Iolite
Lynx Sapphire - Iolite
Sapphire Quartz - Massive Blue Quartz or Chalcedony
Sapphire Spinel - Blue Spinel
Water Sapphire - Iolite
Uralian Sapphire - Blue Tourmaline.
Sapphire treatments and enhancements:
Sapphire is usually heat treated to intensify the blue color, as well as remove inclusions to increase clarity. It is standard industry practice to heat treat
Sapphire gemstones, and most Sapphires used as gemstones have been heat treated.
Sapphire with a natural, unheated color is much more valuable then the heat treated material, and gemstones of good quality can be extremely costly.
Sapphires are sometimes colored through diffusion treatment, which artificially alters the color of the original gemstone. Diffused Sapphires colors include deep blue, bright yellow, bright orange and orange-red.
Diffused Sapphire gemstones are fairly inexpensive.
Because of all the color treatments and enhancements performed to Sapphire gemstones, this information should always be fully disclosed to the buyer, and Sapphire should only be purchased from highly reputable dealers.
Important Sapphire sources include Sri Lanka, Burma (Myanmar), Thailand, Cambodia, Madagascar, Tanzania, Australia, and the U.S. (Montana). The Kashmir region of India/Pakistan was famous for its Kashmir-blue Sapphire, but little material comes
from there today.
Information collected and compiled from The Mineral and Gemstone Kingdom, www.minerals.net and Wikipedia.
Sandra Kemppainen, photos: Wikipedia, The Mineral and Gemstone Kingdom
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