Clarity: Clarity is about how pure a substance is. For instance, to be able to classify a gemstone as “flawless,” it must approach absolute clarity at 10X magnification. Clarity is assessed by the quantity of visible inclusions, fractures, or other internal defects that affect the transparency of the gemstone. Inclusions, are divided in four groups: 1) solid inclusions which maybe of the same material as the host or one completely foreign to it; 2) internal cavities containing gas or liquid or both, sometimes bubble in an inclusion diminishes in size on warming the stone and finally disappears; 3) cracks and fissures filled with gas or liquid which are termed flags or feathers; 4) growth phenomena which includes zonal structures and irregular distribution of colors. The standard terms for high grades of clarity are eye-clean, meaning there are no inclusions visible to the naked eye, or clean, meaning there are no inclusions visible even under 10X magnification.