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The Tools of a Professional Coin Grader

By Steve Feltner - July 3, 2020

I was hired by PCGS as a professional vintage grader almost a decade ago.  At the time, my only industry experience was working at some local coin shops and helping out at a few trade shows a year.  I had taken several grading courses put on by the ANA, which is where my talent was first noticed.  To say that I was both excited and nervous when I walked into the grading room on my first day would have been a major understatement.  But, I had some experience in grading, and I was absolutely willing to learn from some of the best coin graders in the world.  In this article, I hope to describe some of the proverbial tools that professional graders use to their advantage when determining the condition of your coins.

Lighting: One of the most important considerations when grading coins is lighting.  Investing in proper lighting can help avoid costly mistakes from being made.  The best conditions for grading coins is a completely dark room with a single light source.  The best lamps to use have a "bell" end that covers the lightbulb completely.  This allows the light source to be manipulated without any light pollution to occur.  The best bulbs to use for grading coins are 75- to 100-watt incandescent.  My personal preference is 75-watt, as it doesn’t burn quite as hot and isn’t as harsh on my eyes over long periods of time.

Handling: Proper handling techniques are imperative to keeping your coins as original as possible.  Our natural skin oils, sweat, and debris on our hands can have possible negative effects on the surfaces of coins.  Many coins which have been mishandled in the past have fingerprints, spots, corrosion, and other issues.  It is always good practice to wash your hands before inspecting coins.  Any collectible coin should be handled with care and by the edge.  Most coins do not require wearing gloves to handle.  The possible exception to this would be in the case of high-grade vintage copper coins.  Copper is more susceptible to the elements than silver or gold.  When transferring a coin to another person, make sure that the coin is received by the edge.  Alternatively, the coin may be placed on a clean surface like a felt pad or placed into a flip and handed over.  Also, avoid leaving raw coins in open air allows dust particles or moisture to accumulate.  Best practice is to house it in a flip then inside a clean, dry box.

Magnification: Like a carpenter should have the correct tools for the job, so should a grader.  One of the most important tools for a grader is a loupe, or magnifying glass.  Like anything else, and definitely the case for polished glass, you get what you pay for.  Many less-expensive options can create bends and distortion around the edges.  A good glass will have a consistent magnification and clarity from the center to the edge.  The most common loupes found with graders and discerning collectors will be from 5X to 10X power.  Anything higher than 10 will generally only be used for counterfeit detection, variety attribution, and numeric grade limiting problems.  The proper way to use a loupe is to bring it all the way up to your eye, only a few millimeters away, then bring the coin up to the glass until it is in focus.  The most common mistake with a loupe is using it at arms-length to view a coin.  This doesn't give the user a complete field of vision and clarity.

Rotation: Proper rotation under a light source is imperative to seeing any imperfection that a coin may have.  One of the most common mistakes when learning how to grade coins is to place the coin under a light, look at the coin, and immediately determine the condition.  A coin should be rotated under the light freely.  If a certain area of the coin is suspect, turn the coin to another angle and rotate it.  For example, based on the design of Saint-Gaudens Double Eagles, cleaning wipes are easily hidden in the eagle's wings.  If the coin is viewed without rotating it 90 degrees, the cleaning can actually remain hidden.  Another time that a coin should be completely rotated is assessing for full bands on Mercury Dimes.  If rotated 90 degrees, with the bands being viewed "up and down" from the viewer, it is easier to determine if they are full.  Many issues, like PVC or other materials being added to the surfaces of coins, can be determined by holding the coin vertical to the light source.  The added substances will often show by a color change and/or a dead spot of luster on the coin's surface.

Click image to enlarge.
Click image to enlarge.

Numismatic knowledge: One of the most important, and often overlooked, areas of grading is in having a solid foundation of numismatic knowledge.  Understanding the different methods of manufacture, alloys used, and grade-limiting factors are vital for any experienced grader.  It becomes common knowledge after some time of grading that 1926-S Buffalo Nickels are notoriously weakly struck when compared to 1926 Phillies.  As such, 1926-S specimens will not reach the same high grades (MS66 and above) that 1926 Phillies easily can.  The same holds true for 1925-S Peace Dollars, which is why the spread from MS64 to MS65 is so great.  One of the starkest contrasts in regard to strike can be found on Pioneer Gold.  The coins that were minted by private individuals, usually with gold discovered during the gold rush, generally show a lack of design detail that is commonly seen on most government issues.  The coin that I have chosen to illustrate this difference is a beautifully preserved 1850 Moffat $5 that has been graded by PCGS as MS63.  You can see the weakness in strike around Lady Liberty's hair curls and also on the eagle’s feathers.  Many novice numismatists would misinterpret this lack of detail as wear.  However, when you look at the coin, there are no luster breaks on the high points or in the fields.  Contrast this coin with a Philadelphia issue of the same year and same grade.  The Philadelphia coin is razor sharp in strike, but they both carry the same numeric grade.  This is where numismatic knowledge becomes a major factor in the grade of a coin.

Whether you're a novice grader or more experienced, following these simple tips can be beneficial in improving your accuracy.  The fundamentals of grading are absolutely key and should be employed every time you pick up a coin.

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