What is a jeweller's loupe?
By Jared James · Last updated 21 May 2026
Definition
A loupe is a small, portable magnifying glass used by jewellers and gemologists to examine gemstones, hallmarks, settings and surface details that are invisible to the naked eye. It is typically held close to the eye, and the subject is brought up to the focal length rather than the lens being moved around. The standard in the diamond trade is a 10x triplet loupe, which magnifies ten times and uses three corrected lenses to give a clear, undistorted image. Under 10x magnification, the clarity characteristics used to grade diamonds become visible and can be assessed.
Frequently asked questions
- What does 10x mean on a jeweller's loupe?
- It means the loupe magnifies the subject ten times its actual size. The diamond grading industry uses 10x as the standard magnification for clarity grading, which is why SI1 inclusions that are 'eye-clean' at normal distance become visible under a 10x loupe.
- How do you use a jeweller's loupe?
- Hold the loupe close to your eye, not touching but within a centimetre or so. Then bring the object up to the loupe's focal distance, usually a few centimetres in front of the lens, until it comes into sharp focus. Rest your hands against each other or against a surface for stability.
- What is a triplet loupe?
- A triplet loupe uses three corrected lens elements stacked together to eliminate the colour fringing and distortion that single-lens loupes can show. For gemstone grading the triplet is preferred because it gives a flat, clear field across the whole image.
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