Loupe
/loop/
Definition
A small, handheld magnifying lens (typically 10x) used by jewelers and gemologists to examine gemstones, settings, and hallmarks at close range.
The jeweler's loupe is the single most important tool in gemstone evaluation. The standard is a 10x triplet loupe — three lenses bonded together to correct for chromatic and spherical aberration, providing a sharp, color-true image at 10x magnification. This is the same magnification used by GIA and other labs when assigning diamond clarity grades, which is why 10x is the industry benchmark. A good loupe costs $20–$100 and is an essential purchase for anyone buying gemstones. Using a loupe effectively requires practice: hold the loupe close to your eye, bring the gemstone up to the loupe (not the other way around), and use both hands braced together for stability. Loupes come in various magnifications (10x, 20x, 30x) but 10x is standard for trade use.
Usage in the Trade
Loupes are used by gemologists, jewelers, dealers, appraisers, and consumers to inspect gemstone clarity, setting quality, hallmarks, and surface conditions. No jewelry professional works without one.