Assignment 6 - Diamonds and Color Flashcards
What are the basic properties of light?
Light is a form radiant energy that travels in waves.
Light of shorter wavelengths has higher energy that longer wavelengths.
Visible light is a small portion of the electromagnetic spectrum.
What are the possible causes of diamond color?
The presence of impurities (e.g. nitrogen) and structural defects (color centers) are two common causes of color in diamonds.
The distance between two adjactent high or low points of a wave
wavelength.
The range of wavelengths of radiant energy extending from high energy to low energy, including visible light
electromagentic spectrum
The range of wavelengths of visible light from 400nm (violett) to 700nm (red)
Visible spectrum
Process by which a material absorbs some wavelengths of light and transmits others
Selective absorbtion
The process by wich light not absorbed by a material returns to the observer
Transmission
Structural defect that influences an object’s absorption of light and can cause its color.
Color center
A pattern of dark vertical lines or bands shown by certain gems when viewed trough a spectroscope, or a linear graph recorded by a spectrometer
Absorbtion spectrum
How do electrons play a role in selective absorbtion?
Interaction of electrons with visible light causes most selective absorbtion-related gem colors.
Energy difference between the valence band and the conduction band
Band Gap
What are the most common diamond colors?
Yellow and Orange
What diamond defects cause which color?
Nitrogen –> Yellow
Vacancy –> Blue
Vacancy + Nitrogen -> Green
Boron –> Blue
Deformation -> Pink/Red
Inclusions –> Black/Grey/White
Closely spaced grain lines where color concentrates
Colored Lamellae
Emission of visible light by a material when it is exposed to ultraviolet radiation.
Fluorescence
Why isn’t it always possible to determine the color origin in green diamonds?
Because it can result from natural or from artificial irradiation.
What type of luminescence do gemologists commonly use
Shortwave UV
Longwave UV
What produces luminescence in diamonds?
Defects
What are possible fluorescent colors?
Blue (N3), yellow (H3), red (NV)
Emission of visible light by a material when it is exposed to a radiation source
Luminescence
Emission of visible light during stimulation by a UV or X-Ray radiation
Fluorescence
Continued emission of visible light after UV or X-Ray stimulation stops
Photophorescence
What bodycolor can the GR1 defect produce with high nitrogen concentration?
Green
What percent of natural colorless diamonds fluoresce under UV radiation?
35%
What does irradiation create when it displaces carbon atoms in the crystal lattice?
Vacancies
