Embassy Emeralds » A Quick Look at How to Examine Gemstones

A Quick Look at How to Examine Gemstones

Posted on May 26th, 2008 by embassyemeralds

It might seem like a no-brainer to most people of how one should examine a gemstone given a loupe and a stone, but few people outside of the trade actually know how to do it effectively. If you fit that description, then this blog is for you. It’s not an exhaustive look at gemstone evaluation and you’re not going to be pro for having read this, but it should help a great deal if you’re looking for where to start.

Before you begin, you need to be sure you have a few things present:

A 10x triplet loupe – Standard for grading gemstones as required by the U.S. Federal Trade Commission. A triplet loupe prevents distortion at the edges of the lens.

Tweezers – This will keep your fingers from oiling up the stones or your skin color from influencing the color you see. However, many a stone has ‘popped’ free from nervous tweezer grips to be lost or damaged as a result. The best advice is….If you’re not good with tweezers, feel free to use whatever method you’re comfortable with, but know that tweezers are ideal.

Good lighting – There is some debate as to whether fluorescent or incandescent light should be used to view stones, so why choose. If available, view the stones using both types but be sure the light comes from above and/or behind you.

A clean, lint-free cloth – Before the loupe goes to your eye, you should clean the stone to remove any dirt, fingerprints, or lint that may get in the way of making an accurate evaluation.

NOTE: Preferably, you’ll be viewing the stone unmounted. This gives you the best opportunity to view the stone as it really is on its own. Gem settings can greatly influence a stone’s appearance, generally improving the apparent color saturation and sometimes hiding flaws.

With a clean stone and everything in place, you can start your examination. If you’ve chosen to hold the stone with your fingers, be sure to hold it in a manner in which you’re only touching the girdle. With the loupe in one hand brought close to the eye (about 1 inch away), bring the other hand with the gemstone into view by bringing the meaty part of your two hands together. This helps steady the gem hand and tends to be very close to the proper distance to focus properly on the stone with the loupe. Slight adjustments with the gem hand will be necessary as you’ll quickly figure out. You’ll want to rotate the stone and view it from several angles. Focus on the surface to detect any cracks or other exterior damage first and then focus deeper to view inclusions and other features of the interior. With practice you’ll be able to quickly examine stones noting the depth of inclusions and features not plainly visible with casual naked eye observations. This is a particularly good practice with emeralds, because of their included nature.

Besides obvious cracks, on the exterior you’ll want to look for chips, scratches, as well as the quality and alignment of the cut. On the interior, take a look at internal fissures if present, inclusions, and be on the lookout for possible foreign substances that could indicate an attempt was made at dying or fracture filling the stone. If you have very little experience in examining gems, take some time to do some homework beforehand. You’ll want to read about the characteristics and concerns that pertain to the stone and the defects you might encounter during your examination.

If you’re looking at the stone to later have it set, a nice trick you’ll want to try is to place the stone in the groove between your fingers with your hand faced down and your fingers together (as shown above). Your skin will provide a backing to the stone that simulates the color deepening effect that many jewelry settings have on gemstones. It really helps to give you a rough idea of how the stone might look once set.

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