Jewelry Blog

How to Use a Jewelry Loupe

13025 Customer using a Loupe on a Diamond and Sapphire Halo Engagement Ring in Showroom

A jewelry loupe is an essential tool of the trade. A jeweler without a loupe is like a butcher without a knife. The loupe aids in closely examining gemstones, enabling the jeweler to detect features like inclusions and cracks. 

Learning how to use a jewelry loupe is essential when purchasing items like diamonds. It is only by closely studying the stone that you will know the quality and condition of your purchase. 

What Is a Jeweler’s Loupe? 

A jeweler’s loupe is a folding magnifying glass. It has a lens that measures between 18 and 21 millimeters and a standard magnification of 10x. Larger lenses allow more light to pass through them, improving image quality. 

A jeweler’s loupe has a standard 10x magnification because the Federal Trade Commission requires grading at this amplification. Blemishes that are not visible under 10x are inconsequential. Lenses with a higher power also have a decreased focal length and a narrower field of view, making them unsuitable for jewelry inspection. 

Loupes come in various shapes and sizes based on their applications. Gemologists prefer the hand lens as it is easier to handle. You will often see one hanging around a jeweler’s neck like a pendant. 

Diamonds are accessed according to their clarity and color. Therefore, it is essential to view these features before buying a gem carefully. A jewelry loupe will allow you to examine hidden facets of the stone to make an informed purchase. 

How to Use a Jewelry Loupe

Examining Diamond Designs with Loupe

Using a jewelry loupe is not difficult once you get the hang of it. However, it does take some practice to learn how to handle the instrument correctly. Understanding how to use a loupe is valuable as it allows you to identify many aspects of a stone relatively quickly. It is also much cheaper than other gemological equipment, which means that you can easily acquire it for your purposes. 

The steps below will walk you through how to use a jewelry loupe. 

  1. Unfold the loupe and clip your index finger into the provided slot. It will be at the end opposite the lens. You can view the lens from either direction so you can hold the loupe with whichever hand you feel comfortable with. 
  1. Position the loupe directly over your eye. You should press the knuckle of your thumb against your cheek as this position will ensure that your hand remains steady. You can place your elbow on a table for further stability. 
  1. Using your other hand, move the gemstone to within an inch of the lens. Shift the stone around until it comes into focus. 
  1. Inspect the face of the diamond before viewing it from different angles. 
  1. Confirm what you are looking at by comparing it to the diamond’s grading report. 
  1. With a small gem, you should be able to view the entire stone at once. Larger rocks may require you to focus on one section at a time. 

Tips and Mistakes When Using a Loupe 

Examining an engagement ring with a loupe

Learning how to properly utilize a jewelry loupe takes some practice. Here are a few tips and tricks to help you use a loupe. 

1. Select a Loupe With Three Lenses Cemented Together 

These loupes are triplet type, and you can buy them at most optical shops. The triple-type loupe corrects two problems encountered by other lenses. They do not have a hint of color on the edges of other lenses. Triple-type lenses also do not have visual distortion. 

2. Go for Achromatic and Aplanatic 

The best loupe to use is one that is achromatic and aplanatic. The design of an achromatic lens frees it of unwanted external colors. The tight control of the aplanatic lens focal point makes for a sharper image. 

Choose a Jewelry Loupe With a Black Body 

Your jewelry loupe should have a black body. The black color reduces light reflection and does not introduce external light the way that gold or silver would. 

3. Move the Gem, Not the Loupe 

Only move the gem and not the loupe when examining the stone. Keep the loupe as steady as possible to maintain focus. 

4. Use Both Eyes 

It is tempting to close one eye when using a jewelry loupe. However, this may not be ideal. Keep both eyes open to reduce eye strain 

5. Check Your Light Source 

Ensure that you have a good light source before inspecting the stone. The room should not be too dark or too bright. You should avoid intense LED lighting as it tends to be harsh. Overhead illumination would work best to decrease the risk of casting shadows on the gem. 

6. Place the Light Behind the Stone 

To properly see inside the stone, place a light source behind the diamond and shine the light through it. This will help you study the inclusions in the gem. 

This tip may sometimes be distracting in diamonds but works exceptionally well in colored stones.

7. Grade With the Naked Eye First 

Before using the loupe, study the diamond for visible flaws or colors. It is essential to grade the stone with your eyes before placing it under magnification because we tend to see what we expect to see. If you only use the loupe to view the gem, you may miss some crucial features. 

8. How to Prepare a Stone Before Louping It 

Preparing a diamond for inspection ensures that you can sufficiently study all the stone’s facets. These are the things you need to do to prepare a diamond for evaluation. 

9. Clean the Diamond 

Clean the diamond before the inspection to ensure that you will not mistake any dust or dirt on the surface for inclusions. You can clean the stone by soaking it in ethyl alcohol before drying it with a lint-free cloth. Alternatively, you can take the rock for professional steam or ultrasonic cleaning by a jeweler. 

10. Remove the Setting 

A mounted stone is hard to inspect adequately. The setting may not only hide blemishes, but the metal can also alter the color of the gem. Many jewelers use prongs to conceal flaws like cracks or spots. Before inspecting a stone, remove it from its setting so that you can view the entire gem without obstructions. 

Using Tweezers to Hold the Stone

3 Carat I Color Asscher Cut Diamond

Diamonds are notorious for attracting grease. Although your hands may be clean, your fingerprints will probably leave oily marks on the surface of the stone. These streaks may show up under magnification and be mistaken for blemishes. 

When evaluating diamonds, it is better to use tweezers to hold them in place. Clip the sides of the stone gently as a tight grip may damage the edges of the gem. Tweezers will secure the stone and allow sufficient light to pass through when viewing. 

The best tweezers to use are locking tweezers. 

They have a side lock that holds the stone in place. When using tweezers, grasp the instrument between the thumb and middle finger. Your index finger will go in the tweezer opening and be used to exert enough pressure to widen the gap. Flip the diamond facedown with the tweezers. Lower the tool around the stone and slide the lock into place once you have a good grip. 

How to Use a Watchmaker’s Loupe 

Which Loupe To Buy

A watchmaker’s loupe is a magnifying glass constructed to be clamped around the eye and held in place by the eye muscles. Some watchmaker’s loupes have head straps or can be mounted on glasses to prevent straining eye muscles. The design of a watchmaker’s magnification tool allows for hands-free use, allowing the watchmaker to utilize his hands while working. Their magnification varies depending on the needs of the artisan. 

The watchmaker’s loupe is a vital tool when assembling the intricate mechanisms of a watch. The instrument can also help when examining watches or jewelry for quality and condition during purchase. 

A watchmaker’s loupe should be light to cause minimal strain to the eye. It should also be easily portable and not have a magnification greater than 20x. A higher magnification reduces the depth of the field of vision resulting in an image of lower quality. 

This is how to use a watchmaker’s loupe. 

  1. Place the watchmaker’s loupe on your eye and clamp your eye muscles around it to hold it in place. 
  1. Keeping both your eyes open, move the item you are viewing to the field of vision. 
  1. Hold the item about an inch away from the loupe and slowly move it around until it comes into focus. 

Watchmaker’s loupes are helpful when working with jewelry. They are ideal when you need to use your hands while inspecting the stone. An example would be when cleaning a diamond. 

Talk to a Diamond Expert 

Shopping for a diamond engagement ring from Estate Diamond Jewelry

Knowing how to use a jewelry loupe is helpful when purchasing a diamond. It would help if you examined gemstones the same way you would inspect a car before buying it. It is essential to view any inclusions or defects in the stone to determine its value. Learning how to use a jewelry loupe takes some practice. Talk to a diamond expert at Estate Diamond Jewelry for assistance on correctly handling a loupe. They will also advise you on what to look for when inspecting a diamond. 

Are you looking to buy a diamond? With this handy guide, you will learn to use a jewelry loupe to identify a quality gem. 


About Afshin Shaddaie

Afshin moved to New York City in the 1980s, and a few years later, he began his career in the fine and rare jewelry scene. He teamed up with Michael Khordipour, and they've been curating vintage jewelry ever since. He also regularly contributes to Forbes, Rapaport, CNBC, The Knot, and Insider. Afshin constantly travels to international shows and private viewing events in the hope of finding rare vintage rings that will be important enough to make an impression. He is available for appointments at our New York showroom when he's not traveling. In 2019, Afshin authored his book called The Engagement Ring Guide for Men. He is considered one of the world's foremost authorities on vintage jewelry and antique diamonds. His favorite jewelry era is Art Nouveau, and he loves rare Italian jewelry from the 1950s - 1970s. The Natural Saltwater Pearl is his favorite precious jewel.