Chapter 6 Key Concepts & Terms Flashcards
What is light?
Light is a form of radiant energy that travels in waves.
How does the energy of light relate to its wavelength?
Light of shorter wavelengths has higher energy than light of longer wavelength
What is visible light in relation to the electromagnetic spectrum?
Visible light is a small portion of the electromagnetic spectrum.
What is white light composed of?
White light is a combination of spectral colors.
What is the primary cause of color in diamonds?
Diamond color is primarily caused by defects in the crystal lattice.
What tools can gemologists use to observe a diamond’s absorption spectrum?
The spectroscope and spectrometer can help gemologists see a diamond’s absorption spectrum.
What causes most selective absorption-related gem colors?
Interaction of electrons with visible light causes most selective absorption-related gem colors.
Why are diamonds without color centers are colorless?
Diamonds without color centers are colorless due to the lack of visible light absorption.
How do color-causing defects influence electron transitions within a diamond?
Color-causing defects works as energy “steps” within a diamond’s band gap to ease the electron transitions “fueled” by visible light absorption.
What is the most common cause of yellow color in diamonds?
Nitrogen-related defects are the most common causes of yellow color in diamonds.
What is the primary cause of green color in diamonds?
The most common cause of green color in diamonds is radiation
What characteristic is typically found in naturally irradiated diamonds?
Naturally irradiated diamonds usually contain areas of green or brown radiation damage on their surfaces or penetrating into the stones.
What impurity is responsible for the blue color in type IIb diamonds?
Boron impurities are responsible for blue color in type IIb diamonds.
What defect, caused by radiation, can create a blue color in diamonds with low nitrogen concentrations?
The GR1 defect, caused by radiation, can create blue color in diamonds with low nitrogen concentrations.
What is the main cause of color in pink-to-red diamonds?
Deformation-caused selective absorption is the main cause of color in pink-to-red diamonds.
What causes black, gray, and white colors in diamonds?
Inclusions are the main causes of black, gray, and white colors in diamonds.
How does the energy level of luminescence compare to that of the radiation source?
The energy level of luminescence is lower than that of the radiation source
Why is luminescence considered an efficient visual test for diamond identification?
Luminescence is an efficient visual test for diamond identification, it reveals hidden defects in the crystal lattice and can quickly distinguish between natural and synthetic diamonds.
Definition of absorption spectrum?
A pattern of dark vertical lines or bands shown by certain gems when viewed through a spectroscope, or a linear graph recorded by a spectrometer.
Definition of Band gap?
Energy difference between the valence band and the conduction band.
Definition of Color center?
A defect that can influence an object’s absorption of visible light to cause its color.
Definition of Colored lamellae?
Closely spaced grain lines where color concentrates.
Definition of Electromagnetic spectrum?
The range of wavelengths of radiant energy extending from high energy to low energy, including visible light.
Definition of Fluorescence?
Emission of visible light during stimulation by UV or X-ray radiation.
Definition of Luminescence?
Emission of visible light by a material when it is exposed to a radiation source.
Definition of Phosphorescence?
Continued emission of visible light after UV or X-ray stimulation stops.
Definition of Selective absorption?
The process by which light not absorbed by a material returns to the observer.
Definition of Wavelength?
The distance between two adjacent high or low points of a wave.
Definition of Visible spectrum?
The range of wavelengths of visible light from 400nm (violet) to 700 nm (red)
