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Clarity:
A gemstone's clarity grade is directly related to its rarity. Clarity refers to a gemstone's relative freedom from clarity characteristics. Clarity characteristics include inclusions, which lie within the stone, or blemishes, which lie on the surface of a gem. The fewer clarity characteristics, the more rare the gemstone.
Each variety of a gemstone has its own clarity standards. For example, Tanzanite is virtually inclusion-free while Emerald almost always contains clarity characteristics. For this reason, Gemological Institute of America's grading system divides transparent coloured gemstones into three clarity types. This allows gems to be more evenly evaluated, as it takes into account the individual nature of each gemstone.
Each type is further divided into five grading descriptions. Gemologists will first consider the gemstone type and then consider the size, location, number, nature and colour of the inclusions before assigning a clarity grade to a gemstone.
Clarity Types:
Type 1 gems are often virtually free of clarity characteristics. The stones most commonly seen include:
Aquamarine, Green Tourmaline, Kunzite, Tanzanite, Topaz- Blue, Zircon- Blue
Type 2 gems normally contain clarity characteristics. The stones most commonly seen include:
Andalusite, Alexandrite, Amethyst, Ametrine, Citrine, Iolite, Peridot, Ruby, Garnets- all species and varieties, Smoky Quartz, Sapphire- all colours, Spinel- all colours, Tourmaline- pink, blue, red, orange, yellow and partie-coloured (exc. watermelon) Zircon- green, orange, red and yellow
Type 3 gems almost always contain clarity characteristics. These include:
Emerald, Tourmaline-watermelon
