I have a 10X loupe and a 40X (25mm) loupe with led and ultraviolet led's. Also have a 60X hand held microscope with led and ultraviolet led's. A large hand held magnifying glass with both led and ultraviolet led. I also have a digital desk microscope 2000X Yup 2000X. With this I can zero right in to the individual fibers on an edge an actually see the ends of the fibers, not just the fibers. I can see the "grain" of an edge cut. I am also building a light box out of a 5 gal fish tank. The section on equipment in the detecting alterations and reprints have some useful information but is behind considering the current technology (for example it states that 20X is too strong?? Absurd!). A person can buy a powerful digital microscope for under 50 bucks that would have cost 50K not long ago.
Dave. ps all the loupes and glasses I have were very inexpensive (mostly from china via ebay).