The atomic structures of gemstones are similar to their mineral origin, in that their atomic components are arranged in specific patterns, or crystal structures . There are 6 main ..........

Hardness measures a gemstone's resistance to scratching, which is related to the ionic or atomic bonding strengths of the minerals and their chemical components. The most widely used measuring ..........

Toughness refers to how well a gemstone can withstand external mechanical stress, such as impacts from falling or hammering, without breaking, chipping and cracking. Toughness is not necessarily ..........

Cleavage is the tendency of mineral crystals to fracture into defined crystallographic planes. The direction and the availability of cleavage planes are governed by the structures of crystals. The ..........

Like most other objects, minerals differ in their abilities to absorb, reflect and transmit light at various wavelengths, and therefore will produce different colors. Color is also an important ..........

Luster describes the way light reflects off the surfaces of gemstones. Minerals with high refractive index and can reflect lights well are said to have “adamantine luster,” such as diamond, zircon ..........

Transparency measures the degree of light that passes through a gemstone. Transparency of a mineral is closely related to factors such as amount of impurities, inclusions or cleavages. For ..........

Dispersion of a mineral refers to how light is broken down into its individual wavelength components – red, orange, yellow, green, blue, violet and purple -, when it hits the surface of a ..........

Gemstones have a higher density than air, therefore when light enters the gemstone it will slow down and change direction, resulting in refraction. The ratio between the speed of light in the air ..........

When observing gemstones with birefringences, one may occasionally observe differences in shading or color changes. This is referred to as pleochroism (“many color), and is caused by absorption ..........

Chatoyancy, or “cat's eye,” is an optical phenomenon caused by light reflecting off a gemstone with internal fibrous minerals or inclusions arranged in parallel direction. When these gemstones are ..........

Asterism is a type of optical phenomenon caused light reflecting off impurities inside of gemstones, such as fibrous materials arranged in specific directions, mineral, gas or liquid inclusions. ..........

Gemstones may change their colors depending on the angles of light entering into them. Also, gemstones may change colors when shined by lights at different wavelengths. Such property is referred ..........