The Dubay Scale is a counterfeit threat scale of four gradations developed by Dr. Gregory Dubay, a researcher of Chinese-made counterfeit coins. He presently teaches a class for the American Numismatic Association on how to detect counterfeit coins. The “threat levels” are, roughly:
Dubay-1 (D-1) – Obviously discernible counterfeits with very apparently flaws that look “off” to most people with even cursory experience in Numismatics. More often than not they are not made from the right metal alloys.
Dubay-2 (D-2) – Predominantly made of D-1 coins which have been doctored with fake wear or aging and pre-packaged in sets so to draw away from their flaws. Most fake PCGS and NGC slabs on the market today are D-2s, where the slabs, themelves are much more accurate reproductions than the coins they contain.
Dubay-3 (D-3) – These are coins that are close to mint tolerances and have the capacity to deceive collectors and dealers who do not take the time to look closely and are often to mint specifications. Much of the fake bullion on the market (counterfeit American Silver and Gold Eagles) falls into this category as they meet weight, size, and most appearance requirements and are heavily plated in gold or silver so they will pass most scratch and acid tests.
Dubay-4 (D-4) – These coins are all but flawless reproductions and are only given away by difficult-to-discern clues such as the infamous Omega Double Eagles, and counterfeit Micro-O Morgans, some of which even made their way as genuine into Third Party Grading company holders.
We plan to eventually mark The Black Cabinet database listing by Dubay number so that examples can be collated for further research.