Loupe

A loupe ('luːp ) is a simple, small magnification device used to see small details more closely. They generally have higher magnification than a magnifying glass, and are designed to be held or worn close to the eye. A loupe does not have an attached handle, and its focusing lens(es) are contained in an opaque cylinder or cone. On some loupes this cylinder folds into an enclosing housing that protects the lenses when not in use. Three basic types of loupes exist: Simple lenses, generally used for low-magnification designs because of high optical aberration. Compound lenses, generally used for higher magnifications to control optical aberration. Prismatic, multiple lenses with prisms. Loupes are used in many professions where magnification enables precision work to be done with greater efficiency and ease. Examples include surgery, dentistry, ophthalmology, the jewelry trade, gemology, questioned document examination and watchmaking. Loupes are also sometimes used in photography and printing. Jewellers typically use a monocular, handheld loupe to magnify gemstones and other jewelry that they wish to inspect. A 10× magnification is good to use for inspecting jewelry and hallmarks and is the Gemological Institute of America's standard for grading diamond clarity. Stones will sometimes be inspected at higher magnifications than 10×, although the depth of field and field of view become too small to be instructive. The accepted standard for grading diamonds is therefore that inclusions and blemishes visible at 10× impact the clarity grade. The inclusions in VVS diamonds are hard to find even at 10×. Loupes are employed to assist watchmakers in assembling mechanical watches. Many aspects require the use of the loupe, in particular the assembly of the watch mechanism itself, the assembly and details of the watch dial, as well as the formation of the watch strap and installation of precious stones onto the watch face.