Using a jeweler’s loupe
Selecting a loupe:
The first thing to look at is the magnification. Loupes can be found with 2x magnification up to 30x, or even more, magnification. For our purposes it is best to use a 10x loupe since this is the magnification that is used by the gem grading labs to grade diamonds. Less magnification may not show enough detail, while more magnification may give you an unrealistic expectation.
The next thing to look at is the number of lenses a loupe has. The inexpensive loupes tend to have a single lens. These are fine for casual use, but may introduce focus and clarity issues. A triplet loupe has three lenses that correct your magnification to present the clearest possible view and help correct any color issues that may be introduced by reflected light.
And finally, your loupe should also have a black body. The black helps cut down on reflections and does not introduce any color like a silver or gold loupe body may.
Using a loupe:
The biggest mistakes that most people make is not resting the loupe against something to steady their field of view and moving the loupe around. Both mistakes make it difficult to get a consistent and focused view.
Using a loupe really is a simple thing to learn but may take many tries to master. The first thing that you want to do is open up your loupe and hold it up to your eye. I like to hold mine no farther than an inch away. Rest a finger or the back of your hand against your face to help you keep the loupe stable and relaxed.
Now we bring the object we want to view into our field of view. With many loupes you will need to bring the ring, or diamond, within an inch or two of the loupe. Do not move the loupe around, move just the gemstone you are viewing to bring it into view and to focus on exactly what you want to see. That’s it. It really is that simple.