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Fluorescent Light Coin Examinations

To introduce fluorescent light coin examinations, let me quote from a recent article in Road & Track magazine about one of the fastest, most powerful and expensive supercars on earth built by Bugatti: “The final step for each newly assembled Chiron is a painstaking examination under 100 fluorescent lights. NO FLAW CAN HIDE.”

While I cannot take credit for the use of fluorescent light for coin examinations, as virtually its sole proponent for the last 40 years, when its value for both authentication and grading is eventually realized, I hope that future numismatists will forget that it was not my discovery and give me the credit.

I was introduced to fluorescent light for coin examination in 1972 as a rookie authenticator at the American Numismatic Association’s Authentication Service in Washington, D.C. Our setup consisted of a Nikon SMZ-2 Stereo Microscope illuminated by a two-bulb jeweler’s fluorescent bench lamp. As a serendipitous side note, imagine my surprise when that exact same jeweler’s desk lamp I had used 40 years earlier was on my new desk when I was hired by ICG! Apparently, while I was employed at another third-party grading service, ICG had purchased some equipment and furnishings, and my original lamp was part of the deal. Originally, I had modified my lamp by cutting a semicircular piece out of the shade so that the barrel of the microscope could be pushed closer to the light. This let the light beams fall upon the coin in a more perpendicular direction. Now, here was my lamp with the frayed tape still covering the sharp edges in the cut-out shade.

Why fluorescent light and where did that idea come from? I don’t know its origin, but the setup we used was taken directly from the technicians employed at the Treasury Department’s Bureau of the Mint Technology Laboratory, also in D.C. The director of the authentication service, Charles Hoskins, was formerly an employee of the Philadelphia Mint. I didn’t know at the time that Charlie was also a fairly advanced coin collector. After he was chosen to run the newly established coin authentication service in Washington, he was given several weeks of instruction by Treasury Department authenticators using the identical equipment – both the SMZ-2 and the fluorescent lamp.

As I understood it, before the ANA’s Authentication Service came into being, the Mint Lab handled all questions of authenticity from both the government and the public. They were the final authority. Nevertheless, within a very short period of time, the new authentication service had cut their workload to a trickle. On several occasions, agents of the Secret Service even came directly to our office for opinions.

Hoskins learned that fluorescent light is the only type of light to use for coin authentication. The benefits of this setup are easy to explain. A stereomicroscope gives us the needed magnification, while using both eyes at the same time provides the natural depth of field we are normally used to. The fluorescent light provided a non-reflective, uniform view of the surface absent the glare of an incandescent light. Thus, we were able to see imperfections of any kind. Remember the Bugatti? No flaw can hide. Neither can any of the coin’s exceptional qualities because it works both ways. I’ll get no argument here, so let’s move on to the controversial use of fluorescent light for grading coins.

At the authentication service we were required to weigh, photograph and grade each coin for our internal records so we could prove we returned the same coin or identify it if it were stolen. In order to grade as precisely as possible, we removed all the variables from the grade we assigned. Thus a coin’s strike, eye appeal and value did not influence what evolved into a “true” Technical Grading System. Our grading was very strict at the time. Mint State was defined as no trace of wear. Since we were already viewing each coin under our scope using fluorescent light for authentication, it was very natural to grade it at the same time. I’ll stress this again: No flaw can hide. That included the very obvious change of color to a coin’s surface once it was no longer an original Mint State specimen. The fluorescent light made our grading precise. Thus, the same coin was not graded AU one day and MS on a different day. The reverse was also true. Perhaps this “wiggle room” is one of the reasons you have been told for decades to never use fluorescent light to grade coins.

Now, you’ll get no argument from me that bagmarks, scratches and hairlines are the easiest to see when you tip and rotate a coin in a dark room using incandescent light as is done in every professional grading room, but the glare from that light can hide friction on the high parts of the coin’s design. A stereomicroscope is the “equalizer.” Anything that can be seen using incandescent light can also be seen (plus more) by using fluorescent light, both eyes and the microscope. That’s why I examine just about every coin I grade with both a 7X hand lens under a 100 watt incandescent light and a 7X scope illuminated with fluorescent light. I like to see all the coin’s attributes. The only advantage of fluorescent light used with a hand lens is the ability to see rub (loss of luster) on a coin’s high points that is hidden by the glare from a light bulb! Give it a try.

Read more by F. Michael Fazzari