Thermal Conductivity

The thermal conductivity of a material is a measure of its ability to conduct heat.


A talisman is an object, typically an inscribed ring or stone, that is thought to have magic powers and to bring good luck.

Alluvial Deposit

An alluvial deposit is clay, silt or gravel that was carried by a rushing stream and deposited in locations where the stream slowed down.


Reflection is the change in direction of a light wave at an interface between two different media, so that the light is returns back into the medium from which it originated.Your bathroom mirror being the perfect example.


Refraction is the change in direction when a light wave passes from one medium into another. A common example can be seen when placing a stick into water and it appears to bend. In fact, the light from the stick is changing direction as it exits the water and enters the air.


Diffraction refers to the bending of light that occurs when a light wave encounters an obstacle or a slit. The light bends around the corners of an obstacle or aperture.


In mineralogy, lustre is the way light interacts with the surface of the mineral. Many terms are used to describe lustre. Terms such as adamantine, greasy, dull, vitreous and more. A common term is vitreous, which refers to a glassy lustre.


Nacre, the coating that appears on the inside of some mollusc shells, is an organic-inorganic compound. Nacre is also the natural coating applied to pearls by molluscs. It’s a very resilient and strong surface that has beautiful iridescent appearance.


A meetpoint is the point where three (3) or more facets meet.

Gemstone Keel

The gemstone keel is found on certain gemstone cuts, instead of a culet. Cuts such as the emerald cut and the oval cut can’t have a point and instead have an edge called a keel.

Gemstone Culet

The gemstone culet is the point at the bottom of the gemstone. To prevent chipping, in some gemstones the culet has a flat surface rather than a point.


Gemstone facets are usually flat surfaces cut into the gemstone in a uniform and planned pattern. They generally cover all surfaces of a gemstone. In modern times gemstones can have curved surfaces, either concave or convex. The facets must be positioned accurately, according to specific angles, to best reflect the light back to the viewer, […]

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