Featured Authenticating Chinese Part II: Ji Mo Knife

I did the XRF test today, and I am officially concluding that the original XRF data does not remotely correspond to the metallic composition of the coin. That favors very strongly with the authenticity of the piece. Results are in the discussion below.

The device I used had an X-Ray tube that measured about 15mm x 15mm. That meant that the entire 15mm x 15mm area got analyzed.

The material in the patina and the metal of the coin are most definitely not the same. When I analyzed the cleared area on the obverse, the sample area included a lot of the surrounding patina crust. The results for this area were:

Cu 34.34%
Pb 43.96%
Sn 13.55%
Fe 0.66%
Ti 5.46% (yes, Titanium!)

The X-Rays from the transmitter can only excite atoms a few microns into the surface and read the electromagnetic spectra they give off. This means that all patina in the analysis region would have blocked analysis of the metal underneath, so this was a very inaccurate sampling of the metallic composition of the knife. The significant presence of titanium (!) was likely from titanium oxide deposits on the coin, meaning that the patina was severely skewing the results.

After the above run, I decided to analyze the handle area of the reverse as it was the most-cleared area of the coin (though there was still a noticeable amount of deposits left behind). The width of the handle was sufficient to cover the entirety of the x-ray tube. Two tests were run on two areas of the handle, producing the following results:

Run #2:

Cu 53.53%
Pb 20.58%
Sn 28.48%
Fe 0.56%
Ti 0.23%

Run #3:

Cu 54.61%
Pb 19.47%
Sn 20.19%
Fe 1.05%
Ti 0.24%

This shows that the coin is mostly copper and not mostly lead, like I had already concluded above. However, JiMo knives are typically 65-70% copper, with 3-character Qi knives typically being 50-55% copper. So what gives?

As stated previously, the tested areas of the handle were not perfectly cleared, so there was still a noticeable amount of patina left behind from the aggressive cleaning. As demonstrated in the first test, the patina contains an abnormally-high concentration of lead, so this would skew the relative numbers of the other elements down. The ratio of tin to copper in the first test was also abnormally high, which suggests that there might also be a high concentration of tin in the patina as well. adjusting both of these values down would result in a metallic composition that would be in line with genuine JiMo knives.

I stand by my original conclusion that this coin is authentic.

Thoughts @AnYangMan ?

 

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See above post

 

I had an expert examine this coin, and he called it fake for exactly the same reasons I did in my initial examination. So I treated this coin to undo what had been done to the patina to make it look authentic again. I also chipped off some of the patina to analyze its composition and form of the character underneath. The patina was indeed an earthy crust and not a bonded metal, and the character stroke underneath was sharp and uniform.

The colors of the patina are much more apparent now, and the texture is no longer smooth and pebbly.

All of these things confirm my original conclusion. I am now much more confident in calling this coin genuine. The value has also increased as a result.

 

I am so sorry to bring the bad news but this coin is a fake . The patina is not a normal bronze patina and it flakes off, the real patina that happens over ages in underground condition on a Bronze object has tiny azurite and malachite Crystals. The real patina attaches to metal so hard and make it porous in a way that you cant flake it off like this with a scraper . Also presence of Ti in an ancient metal is highly suspicious and indicates the bronze in question is not made in ancient times

 

It doesn’t flake off. It is rock hard. I literally have to use a sharp metal tool to chip it. Nothing else would work. No patina would survive a sharp metal tool

the original exposed area was polished smooth, but it still has pitting. The newly-exposed area has a fine porosity along with pitting.

Yes you can. See above.

TiO is a naturally-occurring compound in soil. It showed up when XRFed in an area with a lot of patina. When the coin was XRFed in an area with little patina, very little Ti showed up.

This coin is genuine.

 

I am still not convinced how patina layer is not absorbed into the metal. I cant see any azurite and malachite Crystals. These Crystal structure is hard to fake and can be visible under magnification and microscope. Based on my experience with Bronze items, the surface under patina would be very much more damaged than what I see in this image. there is not much damage on the base metal but if patina forms over ages you would expect to see much more damage and pitting under patina. You can see some LRB coins posted here in some threads after cleaning to see what type of pitting I mean.

 

Chinese coins are a very different animal. If you look at fully-stripped spades, they won’t have much pitting at all.

And there is plenty of malachite on the reverse.

 

I don't see any malachite its color is green these coins including the spade you posted have no green color patina at all . Their color is brown (unless I'm color blinded) Not a good sign. These are freshly casted metals. The Chinese spade and knives in contrast to what many think, had a fairly good casting craftsmanship. these coins lack such detail craftsmanship and you can see the spade have lumps of metal. Chinese emperors were meticulous about the quality and worksmanship of the mints. so whoever made such a poor cast would have lost his head. So again this is really not consistent with the type of material we see in genuine examples. I highly suggest you seek some third party company opinion on these but what I see is not a good sign.

 

there is plenty of green on the reverse of the knife

Yes, the patina had been fully stripped using vinegar or the like. I’ve included them to show the metal texture under the patina.

No.

the style of the spades (and the knife) are completely consistent with established genuine examples.

How many genuine and fake knives/spades have you seen to get a baseline of what is consistent?

I AM the third party many go to for authentication questions.

 

I went to china and saw the genuine example in many museums including Shanxi and xi'an and Shanghai museum. Based on what I saw the look and feel of the ones I saw in museum totally different , When you look at the example in Chinese museum which are attributed to real excavations, you will notice immediately they have a look and feel that the fakes ones lack. Again no one can prove fake or genuine as there is no evidence but for cleaned coins which lack patina it is very difficult to judge the authenticity as patina is key in determining the authenticity of bronze coins.

 

Their surfaces have also not been messed with like the ones in this thread. That makes a huge difference. In addition, the museum’s collection is based on examples pulled from recent documented hoards, so the patina styles and color are going to be very consistent between examples. Lastly, the Shanghai museum takes the cream of the crop of the hoards found. The satellite museums near the find spots get the brunt of the hoards, such as this museum in LinZi:

http://primaltrek.com/blog/2014/12/02/ancient-chinese-coin-exhibit-at-the-qi-heritage-museum/

Here are some genuine examples on the private market. I’m sure some of them look very different from the ones in museums. In such cases the style (sharpness and font of characters, uniform thickness of stokes, overall shape, rim style, etc.) becomes much more important.



I’m not convinced of the authenticity of the 6-character knife, but the rest are absolutely genuine.

 

I should agree with you that I am not as familiar with these coins and my judgement mostly based on patina . But from the ones you posted , I trust the bottom right corner one. If you see that one has some hard malachite/azurite Crystal which seems pretty hard and attached into the core of metal that is type of patina I would expect on a real ancient bronzes. May I know where these are offered? Ebay ? Are they now offered for sale? Can you send me the link to them please?

 

The top middle one is iffy, but all of the others have very genuine patina styles that are regularly seen on genuine Chinese coins. You should familiarize yourself with those appearances.

The first three were sold in Stacks Bowers auctions, and the last image was from a Chinese auction.

 

@TypeCoin971793, out of curiosity, how does one go about having XRF analysis performed on a coin? I know that there are portable units, but I'm not sure that those are up to scientific standards.

 

I used the XRF in my university’s MSE (Material Science and Engineering) lab