Doctored Coins Detected with PCGS Coin Sniffer’s Advanced Technology

by Professional Coin Grading Service (PCGS) on August 13, 2010 · 0 comments

The PCGS Coin Sniffer™, a process incorporating advanced technology for detecting foreign materials and other enhancements on a coin’s surface, will be used in two roll-out phases on all PCGS Secure Plus™ submissions with the first step beginning in September or October 2010.

Don Willis

PCGS President Don Willis explained the upcoming use of the PCGS Coin Sniffer to the audience at the PCGS Set Registry luncheon in Boston on August 13, 2010.

"When our testing and development are completed, the PCGS Coin Sniffer will analyze the surfaces of coins to detect foreign substances, whether they are organic or inorganic materials. We will begin first with organic substances," said Don Willis, President of PCGS, a division of Collectors Universe, Inc. (NASDAQ).

"We are currently testing the detection of organic materials on coin surfaces and will begin incorporating that process on all PCGS Secure Plus submissions this fall. We are still in the development stage of detecting inorganic foreign materials, such as metals. Implementation of the PCGS Coin Sniffer for inorganic materials is planned for early 2011," he told attendees at the PCGS Set RegistrySM awards luncheon at the American Numismatic Association World’s Fair of Money in Boston on August 13, 2010.

The PCGS Coin Sniffer uses dispersive X-ray spectrometry (EDX), Fournier Transform Infra-Red Spectral analysis (FT-IR), Raman Spectroscopy and other analytical techniques to detect the kinds of materials applied by so-called "coin doctors" to conceal problems with a coin or alter its surface to improve its appearance in an attempt to artificially increase the coin’s value.

Commonly used organic materials applied to coins include plastic resins such as Bondo, putty, caulk, wax, lacquer, varnish, acrylics, paint, ink, acetone, glue, and citric acid.

"Some coin doctors have even used soap, eggs, fertilizer, forehead and nose grease and urine," Wills explained.

FT-IR spectroscopy in the PCGS Coin Sniffer process uses a beam of infra-red light that is reflected off a coin’s surface to detect molecules of foreign substances. Different molecules vibrate at different wave lengths. A complete analysis of a coin’s surface with simultaneous detection of all wave lengths can be completed in less than one minute.

Coins detected with foreign substances are classified by PCGS as "altered surfaces."

Willis explained that some coin doctors use metals to build up certain areas on a coin’s surface, for example, attempting to create a full head on a Standing Liberty quarter, full split bands on a Winged Liberty/Mercury dime or improving diagnostic high areas. Metallic solutions such as solder, indium, Clorox®, iodine and potassium or potash have been applied to alter a coin’s surface.

Beginning next year, the PCGS Coin Sniffer will use EDX technology to analyze elements of coins on the atomic level. The FT-IR technology that will be implemented this fall analyzes coins on the molecular level. In the EDX process, a high-energy beam of electrons is focused on a coin’s surface. Resultant dispersed energy is measured and the atomic structure is determined.

"It’s similar to scanning with an electron microscope," said Willis. "Foreign metals as well as metal fatigue due to high heat from a blow torch or laser can be detected."
Willis also reminded the audience that expanded "plus" (+) grading is now available for all standard submissions and show submissions to PCGS at no additional cost.

Since 1986, PCGS experts have authenticated, graded and certified more than 20 million coins from around the world with a declared value of over $20 billion.

For additional information, visit or call PCGS Customer Service at (800) 447-8848.

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