05:28
Faizan
Black light is a colloquial term for ultraviolet light, the invisible rays that lie beyond the spectrum that we can normally see. Under UV light, some minerals produce a visible glow which vanishes when the UV light is removed. This property is called fluorescence, and it's the same effect you see in black light posters. About thirty percent of diamonds exhibit some fluorescence. This fluorescence can affect the price of the diamond.
Diamonds and Fluorescence
Fluorescence, the visible glow given off by some diamonds under black light, is due to the presence of impurities in the stone. Most gem diamonds contain some impurities. These are responsible for the tints seen in colored or "fancy" diamonds. It is these impurities that cause the diamond to glow under UV light.
Weak fluorescence in diamonds is relatively common, with strongly fluorescent diamonds being much rarer.
The vast majority of fluorescent diamonds glow blue-white under UV, but other colors are possible. A single diamond may even glow more than one color.
Effects on White Diamonds
Under ultraviolet light, some colorless or white diamonds exhibit a blue glow. The prevailing attitude among dealers is that these diamonds are inferior, as the blue fluorescence is thought to make the diamond look cloudy and mean it's less pure.
There is some controversy over this, however, as recent studies have shown that most people (even diamond experts) couldn't tell the difference between weakly fluorescent and non-fluorescent white diamonds under normal lighting conditions. Some people even thought that the supposedly inferior strongly fluorescent white diamonds looked better than the others.
Occasionally a white diamond may exhibit yellow fluorescence. These specimens are very uncommon, however.
The diamond industry sometimes refers to fluorescent white diamonds from the Jagersfontein mine in South Africa as jagers. These were marketed as blue-whites before the term was banned.
Effects on Yellow Diamonds
In contrast to the case of white diamonds, a degree of blue-white fluorescence in yellow diamonds is deemed by the diamond industry to make them more valuable. The theory is that the blue fluorescence cancels out some of the yellow coloration, making the stone look more like the more highly-prized colorless white diamonds.
As with white diamonds, this theory is now disputed as tests demonstrated little difference between the appearance of fluorescent and non-fluorescent yellow diamonds when examined under normal light, even when experts were consulted.
The Premier mine in South Africa has produced many such fluorescent yellow diamonds. Such diamonds from this mine are sometimes known as premiers.
Effects on Pink Diamonds
Like all diamonds pink diamonds are often fluorescent, mostly giving off a blue glow under UV. A minority of pink diamonds exhibit bright orange fluorescence under black light instead of the more common blue fluorescence.
Effects on Blue Diamonds
In common with other diamonds many blue diamonds glow under UV, with blue being the commonest color of fluorescence. Rarely, however, blue diamonds are found that glow in other colors such as red or orange.
The fluorescent properties of the Hope diamond were investigated by the Smithsonian Institution. This famous blue diamond (which popular superstition holds to be cursed) exhibits a very strong blood-red glow under UV light.
Diamonds and Fluorescence
Fluorescence, the visible glow given off by some diamonds under black light, is due to the presence of impurities in the stone. Most gem diamonds contain some impurities. These are responsible for the tints seen in colored or "fancy" diamonds. It is these impurities that cause the diamond to glow under UV light.
Weak fluorescence in diamonds is relatively common, with strongly fluorescent diamonds being much rarer.
The vast majority of fluorescent diamonds glow blue-white under UV, but other colors are possible. A single diamond may even glow more than one color.
Effects on White Diamonds
Under ultraviolet light, some colorless or white diamonds exhibit a blue glow. The prevailing attitude among dealers is that these diamonds are inferior, as the blue fluorescence is thought to make the diamond look cloudy and mean it's less pure.
There is some controversy over this, however, as recent studies have shown that most people (even diamond experts) couldn't tell the difference between weakly fluorescent and non-fluorescent white diamonds under normal lighting conditions. Some people even thought that the supposedly inferior strongly fluorescent white diamonds looked better than the others.
Occasionally a white diamond may exhibit yellow fluorescence. These specimens are very uncommon, however.
The diamond industry sometimes refers to fluorescent white diamonds from the Jagersfontein mine in South Africa as jagers. These were marketed as blue-whites before the term was banned.
Effects on Yellow Diamonds
In contrast to the case of white diamonds, a degree of blue-white fluorescence in yellow diamonds is deemed by the diamond industry to make them more valuable. The theory is that the blue fluorescence cancels out some of the yellow coloration, making the stone look more like the more highly-prized colorless white diamonds.
As with white diamonds, this theory is now disputed as tests demonstrated little difference between the appearance of fluorescent and non-fluorescent yellow diamonds when examined under normal light, even when experts were consulted.
The Premier mine in South Africa has produced many such fluorescent yellow diamonds. Such diamonds from this mine are sometimes known as premiers.
Effects on Pink Diamonds
Like all diamonds pink diamonds are often fluorescent, mostly giving off a blue glow under UV. A minority of pink diamonds exhibit bright orange fluorescence under black light instead of the more common blue fluorescence.
Effects on Blue Diamonds
In common with other diamonds many blue diamonds glow under UV, with blue being the commonest color of fluorescence. Rarely, however, blue diamonds are found that glow in other colors such as red or orange.
The fluorescent properties of the Hope diamond were investigated by the Smithsonian Institution. This famous blue diamond (which popular superstition holds to be cursed) exhibits a very strong blood-red glow under UV light.
