Fluorescence is a phenomenon which causes some diamonds to glow under ultra violet light (UV), which is abundant in natural daylight and some artificial lighting.
The following are the possible grades given to fluorescence:
Faint, Medium, Strong, Very Strong
All grading reports denote the diamond’s fluorescence as well as color. It is estimated that 20%-25% of all diamonds have some degree of fluorescence. Most often diamonds will fluoresce blue, but occasionally yellow or green or an unusual color may occur.
Strong fluorescence can cause a diamond to look hazy or less transparent, however this is not always the case. Years ago the term "blue white" was used to describe the finest of diamonds, many of which had bluish overtones caused by fluorescence. Unfortunately the term became misused and seldom accompanied a diamond that was truly white or blue. It is not appropriate to use the expression in modern times unless the diamond truly possesses a bluish hue.
Generally speaking, a diamond with strong fluorescence, sometimes called an over-blue, which diminishes it's brilliance and gives it a sleepy, or greasy appearance, will cost less than one with faint or no fluorescence. If a diamond is lightly tinted and has faint to moderate fluorescence, it may face up whiter than another diamond of similar lightly tinted color possessing no fluorescence, and may actually cost more.
The following are the possible grades given to fluorescence:
Faint, Medium, Strong, Very Strong
All grading reports denote the diamond’s fluorescence as well as color. It is estimated that 20%-25% of all diamonds have some degree of fluorescence. Most often diamonds will fluoresce blue, but occasionally yellow or green or an unusual color may occur.
Strong fluorescence can cause a diamond to look hazy or less transparent, however this is not always the case. Years ago the term "blue white" was used to describe the finest of diamonds, many of which had bluish overtones caused by fluorescence. Unfortunately the term became misused and seldom accompanied a diamond that was truly white or blue. It is not appropriate to use the expression in modern times unless the diamond truly possesses a bluish hue.
Generally speaking, a diamond with strong fluorescence, sometimes called an over-blue, which diminishes it's brilliance and gives it a sleepy, or greasy appearance, will cost less than one with faint or no fluorescence. If a diamond is lightly tinted and has faint to moderate fluorescence, it may face up whiter than another diamond of similar lightly tinted color possessing no fluorescence, and may actually cost more.
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