This 10x magnification lighted loupe features a 21mm triplet lens and contains six bright white LED lights to illuminate the field of view & stones like never before and its natural white light helps to look at inclusions, a perfect light for viewing diamonds and other gemstones. Another advantages is its achromatic & aplanatic optical glass magnifier for better viewing result, full metal body, UV light (long wave), a slide switch, and indeed has a very fine quality. Its triplet lens system corrects spherical and chromatic aberrations to eliminates color degradation and puts every part of the eide field of view in sharp focus. Some stone fluoresce under UV. 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 gemmologists identify stones. Lights are activated by separate miniature on/off switch located next to the lights. Because the use of the LED light renders the UV light unusable, for practical reasons you can only use one light source at a time, so the loupe functions as either a LED loupe or as a UV loupe. The UV light is used for checking flourescence in diamonds. Diamonds with flourescence will appear cloudy when viewed with the UV light on.This amazingly useful tool is like a microscope it can bring the smallest detail into view! Proper illumination is as important as magnification for seeing close-in detail. Your loupe IS your best 'tester' for gemstones! One of the most highly corrected magnifiers available! Experience the advantage of having a Loupe with UV and LED ligting!!!