EARTHSC 1108 Study Guide - Midterm Guide: Chatoyancy, Labradorite, Refractive Index
11 Apr 2014
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Document Summary
The following questions are to get you thinking about the material. Color: we see color when a material selectively absorbs specific wavelengths of visible light. Luster: external reflection of light in gems surface: depends on refractive index of each stone, the higher the ri the higher the luster, lust in not measurable, so described with names. How is luster related to refractive index (ri): metallic high ri. Inclusions, gas/liquid bubbles, fractures or fissures, grainy or fibrous growths within a crystal. Opaque would most likely be a cabochon, where as a transparent stone would likely be faceted to get sparkle/shine. Understand reflection and refraction of light and how they are related to color, luster and sparkle. Reflection: incident ray reflected ray, angle of incidence = angle of reflection, has to do with luster. Refraction: incident angle > refracted angle, has to do with color and sparkle. Light is reflected in every facet of a stone.
