How-To: GemVue™ Darkfield Loupe

Published: July 2013

The GemVue™ 10x Darkfield Loupe is designed to be attached to the included flashlight, provides 10x magnification as in a standard loupe, but includes a specially constructed area called a viewing well. This well enables you to view a stone and/or jewelry against a black background with strong lateral lighting. This form of lighting is called “dark-field illumination” and is when light enters thru the side of the stone. This type of lighting makes it much easier to identify certain types of inclusions because they standout against the dark background. Dark-field loupes provide a tremendous benefit for anyone who travels and identifies gemstones outside of their laboratory.

Assembling Your GemVue Darkfield Loupe:

To assemble your dark-field loupe, follow the steps below. This tool is designed to fit over the end of the flashlight provided.

1. Place the dark-field attachment on top of the flashlight.
2. Secure the attachment to the flashlight by tightening the screw on the lower portion of the dark-field attachment.
3. Once secure, rotate the flashlight to the “on” position or until you see light being transmitted from the flashlight. Be sure the batteries are strong enough to emit a strong light source.
4. At this point you are ready to start testing stones and/or jewelry.

Getting Started:

To get started using your dark-field loupe follow the steps below.

1. To examine a gemstone secure it in a set of tweezers. To examine a piece of jewelry hold it by its setting.
2. Place the item you want to inspect into the viewing well.
3. Simply bring your eye to the eyepiece at the top of the instrument and view your subject.
4. While looking at your stone or jewelry be sure to position the stone so as to best view the features or inclusions you wish to observe. While you may be able to see a certain feature from one position another angle or lighting direction may reveal even more information about the stone.
5. THIS IS ESSENTIAL part of the testing procedure!
6. As with a standard loupe, examine the stone or jewelry from the top, from the back and the sides through the girdle.
7. When examining thru the girdle, be sure to rotate the stone a full 360°, or if not round, from every side.
8. As you examine from all angles, be sure to tilt and rock the stone keeping it well lit.



Interpreting the Results of the Test:

The dark-field loupe is very useful in terms of examining inclusions in colored stones. Viewing the inclusion against a black background provided by the dark-field attachment, in tandem with strong lateral lighting, makes it much easier to examine inclusions, and better distinguish what they are. You will find it especially useful in seeing curved striae in synthetic sapphires and rubies, and also in seeing flux inclusions.

As important as the dark-field loupe can be when examining colored gemstones, today it is also an essential tool for anyone buying and selling diamonds or diamond jewelry because there are so many fractured filled diamonds in circulation worldwide. Using the dark-field loupe is by far the easiest way to spot these type of stones.

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