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Choosing and Using a Jewellery Loupe

A 10X Loupe

What Is a Magnifier?

Jewellery professionals use a magnifier, also called a loupe (pronounced loop), to inspect gemstones and other jewellery. These magnifiers have special lenses that allow our eyes to focus on an object at a much closer distance than is normally possible, making the object appear to be larger and revealing tiny details we couldn't see with our normal vision.

One Lens or Three?

One: Loupes made with a single lens are generally of poor quality, distorting the object you're magnifying and adding flashes of colour to it.
Three: A triplet loupe is a magnifier that contains three lenses placed together in such a way that distortion and colour problems are corrected.

Magnification Power

Loupes are labelled with a number, followed by the symbol "X," which means "times." For example, a 2X loupe makes an object appear two times its actual size and a 5X loupe shows you a times-five increase.

Best Loupe for Jewellery

A 10X triplet loupe is a good choice for viewing jewellery.
It is the type of loupe used by professionals to grade diamonds and other gemstones. Anything visible through a more powerful loupe, while interesting, isn't included on a grading report.
Look for a loupe with black framing around the lens, because black eliminates reflections that can alter the colour of the object you are viewing.

Loupe Terms to Understand

You will hear other terms when you shop for a loupe. Three important terms are:
Focal Length: The distance that you hold the loupe from an object in order to get the best focus and magnification. As magnification goes up, focal length goes down.
Field of View: This refers to the size of the area you can see through the lens. The diameter of the lens affects the field of view, but so does magnification power--the higher the power the smaller the view.
Depth of Field: This characteristic tells you how far you can move the loupe towards or away from an item and still have the item in focus. The higher the power, the shorter the depth of field.

Beginner's Expectations

Looking through a loupe won't make you a jewellery expert, but even a beginner can learn to spot basic characteristics:
Cracks and chips in gemstones
Larger inclusions and blemishes if you look carefully
A close up view of the quality of workmanship in the piece
Ask your jeweller to point out important characteristics, but don't pretend to be an expert. If you want to use the loupe as a learning tool, you'll need the help and cooperation of your jeweller--and jewellers can spot a fake "expert" just as quickly as they can detect a fake gemstone.

Ask questions. Are there characteristics to watch for to help you determine if a stone is fake or the real thing? What are the signs of a great cut? Are prongs secure and well made? The "best" questions depend on the type of jewellery you are viewing.

How to Hold the Loupe

A good way is to make a tripod of sorts from your hands, placing wrists together and bracing them against your face as you hold the loupe in one hand and the jewellery in the other.
Loupes come with instructions. Practice using yours on any small object to get a better feel for the distance the loupe must be from your eye and the item being magnified. It won't take long to become familiar with the best way to hold it, and after that you'll be hooked--and off to look at every piece of jewellery you own! Have fun.

Joseph Sterling : London Jewellers