This article was originally printed in Numismatic News.
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A recent trip to a jewelry supply center in Sarasota, Fla., opened my eyes to the equipment available to a modern day counterfeiter on a very modest budget. Jewelry casting supplies filled an entire section of the store. There were furnaces, molds, tools, grinders and “how-to” books. As a result of this visit, I’m going to reveal many of the defects found on cast counterfeit coins so that hobbyists can improve their product while at the same time collectors can avoid purchasing fakes. Best of all, this information is available to anyone who cares to search the Internet.
I had access to a small furnace and carbon crucibles in the paleontology lab at the Smithsonian Institution where I worked in the 1970s. On occasion, I would melt my scrap gold into small oval buttons. One day on a whim, I attempted to cast a gold cob coin to put into jewelry. I carved out a cross design into a small block of carbon, put a half ounce button of gold into the center of the cross and placed it into the furnace. When the gold remained a blob and did not flow into the design of my “die,” I placed a flat piece of carbon on top to smash it down while it was molten. When everything cooled, I had a cob-like piece of gold with a distinct cross in the middle. Unfortunately, bits of black carbon were embedded into the irregular surface of the lump and it looked nothing like a genuine coin. I wonder how this experiment would turn out today using modern casting techniques.
Recently, I got to examine a submission of 20 Russian ruble coins from the 18th century grading from XF to AU. Unfortunately, only two of the coins were genuine. The remaining coins covered a broad spectrum with regard to quality and degree of deception. There was one lead copy, well executed, and crude casts, a possible contemporary copy, and several struck counterfeits. At least two examples resembled the modern fakes coming from China. In my opinion, none of the fakes was crude enough to be detected by your average collector. Many should fool the average dealer if mixed in with a small lot of foreign coins.
Most of the fakes had one thing in common, they did not look “right.” So what did I see? All the coins had been cleaned, several very harshly. Many of the coins had a low, flat relief lacking details as if they were circulated; yet their surface looked almost fresh (regardless of the cleaning) when viewed with magnification. The color of the coins was off. Several different washes to mimic age had been applied over scratches and bagmarks. The edge of some fakes was filed to hide the casting seam. This obliterated the edge ornamentation and gave the edge a rounded shape when it should have been more squared-off.
The rims on a few coins were filed, possibly in an attempt to get their weight to conform to tolerance. Let’s take a closer look at them.
A rough and wavy surface common on cast coins is shown in Figure 1 at 40X magnification.
Figure 2 shows a round depression made by a bubble that was trapped inside the mold when the cast was made. The air bubble prevented molten metal from filling this part of the design.
Conversely, the raised, round, pimples and smooth extra metal on the surface of the cast in Figure 3 resulted from bubbles and defects in the mold material as the original coin was copied. Each of these characteristics is common to cast coins.
Finally, let’s examine the surface of the coin in Figure 4 at 40X magnification. Note the smooth, round lumps characteristic of a cast coin.
Careful. This is actually the surface of one of the genuine coins that had been repaired and heated. The lumps on this piece are trapped gas and can be gently squeezed flat; so don’t be too fast to condemn every coin with defects as a counterfeit. Over the years I’ve come to expect that any characteristic of a genuine coin can eventually be seen on a counterfeit and every defect seen on counterfeits can be found on genuine coins.