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Message:: [QUOTE="TypeCoin971793, post: 3775990, member: 78244"]I recently bought a rare and potentially extremely-valuable knife coin where the dealer was uncertain about its authenticity. It was marketed as a contemporary counterfeit because the consignor (a friend) had XRF data showing the coin to be majority lead. I liked contemporary counterfeits, the coin looked ancient enough, and the price was right, so I bought it. I know the collection, so I knew this coin had a pre-1990 provenance. About a year and a half ago, I posted a thread where I worked through a logical analysis of exceedingly rare coins in an effort to authenticate them. <a href="https://www.cointalk.com/threads/authenticating-exceedingly-rare-chinese-coins.321153/" class="internalLink ProxyLink" data-proxy-href="https://www.cointalk.com/threads/authenticating-exceedingly-rare-chinese-coins.321153/">https://www.cointalk.com/threads/authenticating-exceedingly-rare-chinese-coins.321153/</a> I think it would be interesting, as well as helpful to those interested in ancient Chinese coins, to repeat the same exercise for this coin. My Process I always start from “what do I see on the coin” and compare the observations to to what I would expect from a counterfeit or genuine coin. To fit snugly in one of the two categories, any additional observations must be plausibly explained. Once this process is completed, I have a pretty solid conclusion about the authenticity of the coin. The three main aspects analyzed on this coin are the style, the patina, and the metal. The Style Qi knives were cast to an amazingly high quality, especially the 4, 5, 6+ character knives. This knife is a five-character JiMo knife with the inscription 即墨之法化(“Jo Mo Zhi Fa Hua”). [ATTACH=full]1009293[/ATTACH] All Qi knives have very sharp character strokes and lines. The rims on the reverse can often have a flattened “worn” appearance. The font of the characters must match those of known genuine specimens (not necessarily an exact match because the moulds were hand-made). There should not be random gaps in the strokes. The circle around the hole at the end of the handle must have rounded edges (no flat edges like that on modern coins. The right, obverse rim must terminate at the joint of the blade and handle. The width of the handle must be relatively wide compared to normal Qi knives (the knives whose first character is “Qi”). On the subject coin, all of the character strokes and lines of the design are very sharp. The patina buildup on the characters makes them seem thicker, but there are areas where the patina is chipped away where the sharp strokes can be seen. The fonts match known genuine coins. The shape of the coin is consistent with genuine coins, though the handle is on the thinner side of acceptability. The edges of the hole are rounded. Therefore, the style is consistent with genuine coins. This is very important as it is one of the hardest things to get right. There are gaps in some of the lines on the handle, but they appear to be due to legitimate corrosion. When such coins are used to create fake moulds, the inscriptions would have random gaps without any apparent corrosion, such as the fake spade below. [ATTACH=full]1009295[/ATTACH] Here are two genuine Qi knives. Note how sharp all of the design elements are. [ATTACH=full]1009302[/ATTACH] [ATTACH=full]1009301[/ATTACH] Here is a counterfeit 6-character knife from the 1980s, which was considered state-of-the-art in the day. Note how the lines in the handle on the obverse are thick and are somewhat softly blended with the surface. The reverse is extremely soft and completely unlike genuine coins. [ATTACH=full]1009299[/ATTACH] Here is a lot of six genuine knives from a recent auction (so not mine) which excellently portray the correct style of these knives. [ATTACH=full]1009300[/ATTACH] The Patina The patina, and in particular the transfer patina on the upper reverse, originally sold me on this coin as ancient. The crusty outline of another knife on the reverse only forms when coins are fused together for thousands of years. The coloration from the picture was also believable for an ancient patina. In hand, the patina of this coin initially gave me very bad vibes. It looked glossy and had a smooth, pebbly texture to it. The patina on the reverse was very dark, almost black. This made be think that the coin was cast with a patina texture and painted over (or otherwise treated). This is not uncommon when counterfeit moulds are made from genuine encrusted coins. Bad feelings aside, I examined closer. If this was the case, then I should see ample evidence that there was no patina layer on the coin. There should also be a bunch of raised metallic bumps. On genuine coins, there would be no bumps because of the high standard to which the moulds were made. On the obverse, there is a section where the patina was broken away. Looking at the edges of this break revealed that there were two distinct layers of patina. This was verified be looking at the various design elements and seeing chips which revealed two clear layers. The dark patina on the reverse was problematic because it was roughly the same color as the metal. However, there were some slight greenish hues, especially on the knife outline, indicating the formation of hard malachite. The rough-ish texture on the reverse also does not appear to be metal when compared to the metal that is exposed. The exposed metal is smooth and has some pitting from corrosion, but no raised features. A trusted friend pointed out that the obverse had a location where the patina was “peeling”. On fake coins where the patina was accelerated, the patina is often soft or flakes off easily due to poor bonding with the metal. This was his concern. This is easily seen on the reverse of the fake 6-character knife. [ATTACH=full]1009296[/ATTACH] I tried picking off some of the patina with my fingernails, and the patina was amazingly hard. No crust at all has come off, not even dust-sized bits. This indicates that the patina is very well-adhered to the surface of the coin. So I examined the “peeled” area further. There was evidence that it had been vigorously cleaned with some very light scrape marks visible. There is a dirty halo around the interior of the “clean” area where the (metal?) brush could not easily get to. Perhaps someone had tried brute-forcing the patina off and gave up? There are also small areas of red patina in the metal in this clean area. This is the same patina that is on the reverse of the four-character knife, and I see this relatively often on Qi knives. This means that the patina reached deep into the metal, very much implying that the patina is indeed ancient. Some additional observations and potential explanations:<ol> <li>There are two knife outlines on the upper reverse. Based on the placement of the outlines, they could not have been overlapping in the ground, and there are no knife designs that could have produced that singly. I do not have find-spot data, but I’d wager that the two knives in contact were separated by earth movement (earthquake, plowing, etc.) and then rejoined to form the second image.</li> <li>The patina is very glossy. Generally this is not a good sign, but the evidence of a harsh cleaning on the “peeled” area would explain the glossiness. The evidence of a harsh cleaning means that the patina well-bonded to the coin and is thus ancient.</li> <li>The black/dark patina, while uncommon, is not unheard of. I generally see it on Chinese coins with abused surfaces, such as the Qi knife pictured below.</li> </ol>[ATTACH=full]1009294[/ATTACH] The Metal The reason why the consignor believed this coin to be a contemporary counterfeit was that an XRF analysis of the coin had the following results: Cu 15.6 %Pb 67.0 %Sn 10.7 %Fe 6.7 % In contrast, the genuine 4-character knife had the following results: Cu 66.3 %Pb 14.9 %Sn 17.1 %Fe 1.7 % However, in-hand, I can guarantee that the XRF results are not correct. There are areas where exposed metal was worn, and a brassy color was exposed (shown below, lower right rim). Qi knives are supposed to have a brassy color, and lead should have a more gray appearance. In addition, resonance tests further conclude that there is not a predominance of lead. I believe that the Cu and Pb results got switched between the machine and the inbox. [ATTACH=full]1009297[/ATTACH] The resonance of the coin was testing by holding the coin as below, lightly tapping it in the middle and hearing/feeling the response. The 4-character knife had some resonance, but it did not ring much, which implies some crystallization of the metal. The fake 6-character knife hummed as expected because there was no metal crystallization. The subject coin has significantly more resonance than the 4-character knife, but also much less than the 6-character. From this, there is some crystallization of the metal. Exactly how much is very difficult to tell. [ATTACH=full]1009298[/ATTACH] Conclusion The style is exactly what is expected when compared to genuine coins, and the patina has ample evidence that it is ancient and not cast into the metal. The resonance and observation of the color of the metal highly suggests that the XRF results are not to be trusted and that the composition is likely consistent with genuine knives. The comparative resonance between known genuine and counterfeit examples suggested that the metal was crystallized to some degree. With all of this said, I am concluding that this knife is fully-genuine. If there are any flaws to my logic, or if there is something I overlooked, feel free to tell me. I would like to know. The cleaning that made the patina look unnatural severely hurt the value of this coin. Collectors (like myself) prefer coins where authenticity is readily apparent (like in the lot of six posted above). However, after my analysis, I would be sufficiently confident in the authenticity to pay up for it if offered to me again. Since I have been wanting an example of this type for years, I am very happy. <img src="styles/default/xenforo/clear.png" class="mceSmilieSprite mceSmilie1" alt=":)" unselectable="on" unselectable="on" />[/QUOTE]

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