Color Types for Spinel

Spinel

Spinel is the magnesium aluminium member of the larger spinel group of minerals. It has the formula MgAl2O4 in the cubic crystal system. Its name comes from Latin "spina" (arrow). Spinel, (Mg,Fe)(Al,Cr)2O4, is common in peridotite in the uppermost Earth's mantle, between approximately 20 km to approximately 120 km, possibly to lower depths depending on the chromium content.

Spinel has long been found in the gemstone-bearing gravel of Sri Lanka and in limestones of the Badakshan Province in modern-day Afghanistan and Tajikistan; and of Mogok in Burma. Recently gem quality spinels also found in the marbles of Luc Yen (Vietnam), Mahenge and Matombo (Tanzania), Tsavo (Kenya) and in the gravels of Tunduru (Tanzania) and Ilakaka (Madagascar).

Pastel

Pastels or pastel colors are the family of colors which,when described in the HSV color space, have high value and low to intermediate saturation. The name comes from pastels, art media characteristic of this color family. The colors of this family are usually described as “soothing”; “soft”; “near neutral”; “milky”; “washed out”; “desaturated”; and lacking strong chromatic content.

Color Types for Color Change Spinel

A brief description of the color types for color changed spinel used at Agl Thai

Laboratory Gemology.

As color-change spinel, exhibits different colors in different light. Color change spinel usually grayish blue in outdoor light (daylight) andviolet to purple under incandescent. The color change effect is caused by the interaction of the spinel, which absorbs specific wavelengtl light, and the light-source, whose spectral outut varies depending upon the illuminant.