Term
|
Definition
| process by which a material absorbs some components of visible light and transmits others |
|
|
Term
|
Definition
| a pattern of dark vertical lines or bands shown by certain gems when viewed through a spectroscope |
|
|
Term
|
Definition
| a gem colored by trace elements in its crystal structure |
|
|
Term
|
Definition
| a gem colored by an element that is an essential part of its chemical composition |
|
|
Term
|
Definition
| elements that can selectively absorb some wavelengths of visible light and produce color in gems |
|
|
Term
|
Definition
| emission of visible light by a material when it's stimulated by ultraviolet radiation |
|
|
Term
|
Definition
| a process where the electrons that selectively absorb light are passed back and forth between neighboring impurity ions |
|
|
Term
| Intervalence Charge Transfer |
|
Definition
| a process where two impurity atoms separated by another atom can still exchange electrons to selectively absorb light |
|
|
Term
|
Definition
| a small defect in the atomic structure of a material that can absorb light and give rise to a color |
|
|
Term
|
Definition
| change in speed and possible change in direction of light as it travels from one material to another |
|
|
Term
|
Definition
| when a gem's crystal structure splits light into two rays that each travel at a slightly different speed and direction |
|
|
Term
|
Definition
| when a gem's crystal structure doesn't change incoming light other than by refraction and absorption |
|
|
Term
|
Definition
| direction of single refraction in a doubly refractive gem |
|
|
Term
|
Definition
| when a gem shows different body colors from different directions |
|
|
Term
|
Definition
| an unusual optical effect displayed by a gem |
|
|
Term
|
Definition
| interaction of two light rays traveling in the same path |
|
|
Term
|
Definition
| the flashing rainbow colors in opal |
|
|
Term
|
Definition
| a special kind of interference phenomenon that breaks up white light into its spectral hues |
|
|
Term
|
Definition
| a broad flash of color in labradorite feldspar that disappears when the gem is moved |
|
|
Term
|
Definition
| a rainbow effect created when light is broken up into spectral hues by thin layers |
|
|
Term
|
Definition
| the cloudy bluish white light in a moonstone caused by scattering of light |
|
|
Term
|
Definition
| bands of light in certain gems, caused by reflection of light from many parallel, needle-like inclusions or hollow tubes |
|
|
Term
|
Definition
| crossing of chatoyant bands, creating a star in the dome of a cabochon |
|
|
Term
|
Definition
| a glittery effect caused by light reflecting from small, flat inclusions within a gemstone |
|
|
Term
|
Definition
| a distinct change in gem color under different types of lighting |
|
|
