The light is used for checking fluorescence in diamonds. Diamonds with fluorescence will appear cloudy when viewed with the light on. Fluorescence is not 'diagnostic' but, as with most tests, it eliminates some possibilities, opens other possibilities, suggests which other tests to carry out, and that's how gemologists identify stones.
10X Magnification Jeweler Loupe Triplet Lens Magnifier with 6 LED
20x MAGNIFICATION with LED & UV Light, 21mm Lens Diameter, Triplet lens, Metal (Aluminum) body PROFESSIONAL KIT SET: includes 20x Jewelry Loupe,
20x Magnifier Jewelry Loupe LED UV 21mm Triplet Lens Optical Glass, Pocket Gem Magnifying Tool Jeweler, Stamp Philatelist, Coin Numismatic
10x 21mm Loupe Jeweler Magnifier LED UV Light Triplet Lens
Gain Express 21mm Jeweler Loupe 10x Magnifier With LED and UV Light for sale online
3 Pieces 10X / 20X / 30X Jeweler Loupe Glass Diamond Loupe Metal Round Body Jewelers Eye Loupe Magnifier Magnifying 21mm Lens Diameter Silver Color : : Office Products
30x Loupe Magnifier 21mm Mini Silver Metal Triplet Pocket Illuminating Eye Magnifying Glass With 2 Led Light For Watch Stamps Jeweler Diamond : .in: Office Products
This 10x magnification lighted loupe features a 21mm triplet lens and contains six bright white LED lights to illuminate the field of view & stones
GM11 Mini 10X Jeweler Loupe Magnifier + LED & UV light, 21mm lens
10X Illuminated Jewelers Loupe Magnifier with Interchangeable Reticle Scale, LED Light, 25mm Field of View, for Jewelry,Gems, Coins, Hobby Tool (3 Glass Scale Chart) : : Office Products
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Mini 30x 30x21mm Loupe Magnifier Magnifying Triplet Jewelers Eye Glass Jewelry Diamond
30x Loupe Magnifier 21mm Mini Silver Metal Triplet Pocket
MAGNIFICATION: 20x Power magnification, LED and UV Lights, 21mm lens diameter The body is made of metal aluminum and a black frame. BLACK in color with a protective case, cleaning cloth and lanyard cord. A ready-to-go kit set designed for both hobbyists and professionals.
10x 21mm Loupe Jeweler Magnifier LED UV Light Triplet Lens Magnifying Gem Optical Tool Achromatic Aplanatic Foldaway Pocket Black Frame for Inspectin
MAGNIFICATION: 15x Power magnification with LED and UV Light, 21mm lens diameter Emits a cool bright light that produces bright image and good
Jewelers Loupe 10X 15x 21mm Jewelers Magnifying Glass Loupe magnifier Coin Magnifying with Light Jewelers Loop for Gems, Jewelry, Coins and Trichomes