Counterfeit Detection: Altered Date Poland 10 Zlotych

Posted on 8/9/2022

The last digit of the year on this coin holds a clue about its true identity.

The Polish-Russian dual-denominated coinage struck under the reign of Tsar Nicholas I is historically interesting, appeals to a wide variety of world coin collectors and contains several key or better dates in their respective short-lived series. While a common-date example of a 1.5 Roubles / 10 Zlotych piece in lightly circulated, problem-free condition can be acquired for under $1,000, several date and mint master combinations exist that are extremely rare and valuable.

While the 1839 examples struck under mint official Nikolay Grachov do not have the lowest mintage for the series, they have the highest published values for non-proof coinage in the Standard Catalog of World Coinage. The last published sale for an example of this date and type that was described as a circulation issue piece brought $97,500 before buyer’s fees in 2014 as a raw coin graded MS 62 by a Russian auction house.

As such, this date and mint master combination creates a lucrative opportunity for a skilled coin doctor to “create” an 1839 example by altering the last digit of the date to a 9 from one of its more-common-date brethren of the same type, such as an 1833-36 piece. Recently, NGC received an invoice containing such a coin. By using both visual surface analysis as well as die matching, it was conclusively proven that the example sent to NGC was an 1836 that had been altered to appear as an 1839.

Close up of the altered date
Click images to enlarge.

As seen in the above photo, immediate suspicion was rendered when examining the date of this coin. The ‘9’ in the date is of a higher relief than the other digits, with an odd green residue surrounding it. Curiously, this residue is not found anywhere else on this coin. This raises a red flag as oftentimes, after altering a date, coin doctors will attempt to cover up their work by obscuring the surrounding metal to hide a seam, tooling marks or color change as a result of metal manipulation.

While these factors by themselves are not conclusive enough to condemn this coin, heightened suspicions led to additional research to die match this coin to a more-common-date example within the same series. Fortunately, this series is relatively short in length and the die state of this specific coin is quite unique, which made conclusive die matching an easy undertaking.

The altered coin. The obverse has a rim cud from 2 to 3 o’clock, and the reverse shows extensive die cracks, unique date position, die rust under the “1” in “10 ZLOT”, and rust just above and to right of л in рубля
Click images to enlarge.

Using this unique reverse die cracking as a guide, the exercise of finding this same die cracking and rust pattern on a common-date example of this type could begin. Eventually, an 1836 example was found in a prominent Polish auction house that was both an obverse and reverse die match. This conclusively showed that the 1839 example submitted to NGC could not have been struck in 1839 and had to have been an 1836 that had been altered to appear to be an 1839.

Legitimate example sold by a well-respected Polish auction house showing the same die features and flaws as the “1839” piece, thus proving that the coin sent to NGC was an altered date.

Altered dates and mintmarks are some of the most difficult alterations to catch, as the coin itself is genuine and only a very small part of the coin has been subjected to metal manipulation. Further, one must have a fairly intimate knowledge of coinage types and series in order to know key dates.

NGC takes great care in determining the authenticity of the coins that are sent in for grading, and the methods by which this coin was proven to be altered are a testament to this care. And in the unlikely event that an authenticity issue should arise with an NGC-graded coin, NGC has the most comprehensive guarantee available for certified coins to protect all parties in the marketplace.

Did you know? NGC has created a comprehensive Counterfeit Detection resource to help collectors and dealers identify counterfeit and altered coins. Visit

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