What’s a loupe? What’s it for? How do we use it?

Jewelry Appraisal LoupeA jewelry appraisal loupe is the most popular gem and jewelry instrument or tool. It is portable and gives us the ability to assess gems and jewelry efficiently. A loupe with a black housing is a magnifier that is fully corrected for both chromatic and spherical distortion, (or in scientific terms, aberrations); meaning, fully corrected for color and flatness of field.  A regular magnifying glass will make print larger, for example, but, may discolor and distort the edges of an object at the outer portion of the glass. These distortions create a variety of problems for grading color and clarity, for identifying inclusions and ultimately, may cause an incorrect identification of a gemstone altogether!

We use a 10X, (10 times the magnification of the naked eye) loupe mostly. When purchasing one, make sure to ask for a 10X triplet. A triplet contains a lens for magnification, one to correct color aberrations and one to correct linear aberrations. There are numerous scales of magnification available. One might choose a 20X loupe, for example, in order to see a specific inclusion more clearly; however, we risk missing the whole picture when we focus solely on one characteristic. Our depth of field has been minimized. For now, let’s leave the higher powered loupes to those instances when we need to hone in on something especially curious and choose the 10X loupe as our constant gemological companion.

Diamond is the only gemstone for which we use a 10X loupe to grade clarity. We may use no more and we may use no less! (See FTC regulations on diamond grading).We might need magnification to identify and separate gemstones, but, clarity grading for all other gemstones is performed solely with the naked eye!