Antoinette Matlins has been writing the definitive buying guides for gems and jewelry for the past two decades and every one of her books has a section on how to use a jewelry loupe properly. First step is to start with a good loupe. I’m shopping for a better one myself, so I asked her what to look for.
There are a lot of jewelry loupes out there. Which work best for examining gemstones?
Nikon Precision 10x jeweler's loupe
A proper loupe for gemology or jewelry has to be a ten-power (10x) triplet – three lenses fused together to eliminate distortion at the edges and color fringing. You know those big magnifying glasses you used to see elderly people use? Anything viewed through those gets blurrier and blurrier the further you get from the center. A triple-layered lens corrects that.
I have a generic loupe that’s labeled a triplet but I’ve heard many so-called triplets are actually doublets. Is that true?
Absolutely. I see doublets labeled all the time as triplets.
How can I tell if a loupe is really a triplet?
You can tell the difference by the amount of distortion at the edges or color fringing. To test a loupe, hold it a half-inch from newsprint and make sure everything is in focus from one edge to another. Then hold it over flat white paper. If it takes on a beige tone, it’s not a triplet.
How much should I expect to spend?
The reality is that you cannot buy a proper, absolutely correct 10x triplet loupe that is exactly what it should be for under $30. When you see them advertised for less, they’re not fine, properly-corrected loupes.
Bausch & Lomb Hastings triplet magnifying loupe
Which brand do you recommend?
Bausch + Lomb has a wonderful reputation for top-of-the-line loupes. There are also loupes made by Nikon and Zeiss but they can accede $100. I don’t know that you need to spend that kind of money. Bausch + Lomb offers a very fine, optically-correct gemological loupe for about $50 which is, in my opinion, the best value for the money. Because it has a smaller diameter in the loupe area, some people complain that you have to move it around to take everything in. But you’re looking at – or for – microscopic things inside or on the surface of a stone. A smaller diameter is actually better for gemological purposes because it helps you focus more critically and precisely.
You can learn a lot more from Antoinette Matlins at Jewelry Camp 2010, held at New Rochelle College, NY, July 16-18.
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I disagree with the comment about not being able to buy a decent loupe for under $30, I have just got a excellent loupe for $23 i took the lens out and can see it is made of 3 layers of glass, so is a genuine triplet, plus its achromatic and aplanatic.