3 - Color and Value Flashcards
(47 cards)
Near-colorless
G-J
Colorless
D-F
Faint
K-M
Very Light
N-R
Light
S-Z
Normal color range
D-Z, colorless to light yellow, brown, and grey
Of the color components hue, tone, and saturation, what does the GIA scale describe?
Tone and saturation
Depth-of-color
The combination of tone sand saturation that determines how noticeable a color is.
How do mountings affect apparent color?
A complimentary mounting can make stones in the G-I range appear colorless. GIA does not grade mounted diamonds.
What range appears nearly colorless to the naked eye?
J-L
At which grade will an individual start to see color to the naked eye?
Beyond M.
Masterstones
a set of color comparison diamonds that defines GIA’s color grades in the normal range.
What are the three factors that consistent color grading depends upon?
1) Masterstones
2) Environment
3) Grader
When is it appropriate to use “color memory” to grade?
Never. Always compare with a set of masterstones.
Where are color differences more visible?
Subtle differences are more visible through the pavilion, so the color is graded table-down.
What are the best colors for your lab?
Neutral grey, white.
How do you obtain proper lighting for grading color?
Use steady fluorescent daylight bulb.
How can a grader be at their top game?
Stay up to date on training, maintain good health habits.
Fluorescence
Emission of visible light by a material when exposed to UV radiation.
Ultraviolet (UV)
Light wavelength that’s invisible to the human eye.
In what % of diamonds can you see fluorescence?
About 35%
In what colors does fluorescence manifest?
Blue is most common, possibilities include white, yellow, and orange.
How can fluorescence enhance a gem?
Blue fluorescence can mask yellow color.
How can fluorescence detract from a gem?
Too strong fluorescence might make a stone look cloudy or oily.
