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Wilhelmina 1925-1933 10 gulden ping test


Metallurgic

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When I usually buy coins I prefer using respectable dealers 

 

I run some tests myself such as weight and dimensions with digital scales and calipers as well as the ping test. 

I recently came across a very good app "precious coin tester" and run tests to my gold coins such as sovereigns, marks, drachmas and gulden. 

 

They have all cleared fine and scored a 3/3 of the ping test, including some 1875 Willem 10 gulden but... 

3 out of 3 of my 1925-1933 wilhelmina 10 gulden coins scored 1/3 on the test.

The thing is they are all bought from different dealers. I have tried to run tests using custom weights and still the same, I thought they might be of lower gold content but if I lower the finess then the coin fails the test so that might not be the case. 

 

Might be just the case that the app doesn't recognize the coin properly because of the wear?

Can anyone that has in his/her possesion  a 1925-1933 10 gulden run the test so we can cross check the results?

*all the other coins  I have tested including the 10 Willem gulden(that passed) are in AU condition while the 10 gulden wilhelmina are all xf or lower. 

 

Thanks and sorry for the long post!! 

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Problem solved

I have send an email with the sound, I quote the reply:

"Our first analysis shows that these wilhelminas seem to have a slightly higher resonance frequency (higher sound) than Willems usually.

( This slight difference may be due to the different obverses, or the 10% complementary metals inside the coin (silver vs. copper, for example). )
We would need the Willem sound data to confirm our analysis, then we can take this into consideration and update the ratings accordingly. "
 
I recommend the app for both silver and gold  coins. 
 
Hope this is helpful for future reference
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Hi, I noticed that the app has them catalogued as 6.73 gram weight, but another source I use says they're 6.72 gram. I also got 1/3 rating but after I change the weight to 6.72 gram I get 3/3.

I don't have a good scale to weigh them myself but I'm inclined to believe the weight is 6.72 gram. Maybe you might get good results if you try correcting the weight manually like I did.

1897 gold coin:

 

Screenshot_20200829-140609_Precious Coin Tester.jpg

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1898 good coin came back 3/3 with default 6.73 weight setting. I'm using another 10G gold coin to ping to get a clean sound. 3/3 as well with 6.72 grams. I do notice you have to get a proper reading for a good result, so make sure your pings sound clean, no background noise and have a good microphone.

My 1911 and 1925 coins score 1/3 no matter what I do. I can also hear it sounds slightly less clean. 

Unfortunately I don't have the equipment to further investigate, such as a spectrometer or a sensitive scale.

 I am inclined to contact my LSC about the inconsistencies and listen to his opinion. I assume there is a good reason for it, these old coins all have a unique shape and weight due to wear and different designs and maybe they did switch different base metals or made production errors leading to imperfect ratios.

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Hi guys many thanks for your inputs, propably has to do with the app, as different date runs have different composition of complementary metals thus the sound variation

 

I suggest you submit your results to the app developers so they can update their results. 

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  • 2 months later...

Update, please re-run tests, all should be fine now

 

"Hello Nik,

 
We hope that you are doing well.
We have recently updated the application (version 0.9.10) to take the speciality of these Willems/Wilhelminas coins. The score should be corrected.
Please don't hesitate to inform us if you find other unusual cases.
 
Thanks again for your help!
 
Best regards,
Precious Coin Tester team"
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