Please Post Your Coins Which Have A Hemispherical Depression

Fyi, when I had access to a few Rockwell scales used for hardness testing at the production plant I used to work at. Note: not mint related.

At the time it never dawned on me to test a coin. We had specific harden steel pucks used for calibrations prior to testing material intended to be machined or retested after.

I was on the communication side of things. Establishing and maintaining serial communication for uploading data through the network. Wishing now I had ask to experiment with some coins. I'm thinking others have thought of that. Thanks, Doug.

Sadly in todays world, there're probably be fists a flying. Thanks, Doug.

Here is a coin that I think exhibits Rockwell Test Marks (even though I have not yet convinced Mike Diamond that they are!)

I think that evidence to support such a claim will always be circumstantial, and thus subject to debate. However, if the following criteria are met, the odds are indeed quite high that the subject coin has undergone Rockwell Testing.

The criteria are:
the indentation has the same hemispherical cross-sectional profile as a Rockwell Test Mark AND
shows the same depth as a Rockwell 15T test mark AND
has the same diameter as a Rockwell 15T test mark (adjusted for the strike) AND
does not leave a pressure ridge AND
does not leave an anvil effect (bulge) on the opposite side of the coin AND
the coin shows 2 or more such indentations (reflecting Rockwell testing protocol)

Martin D86 thanks for posting!

While it is intriguing, I think it does not qualify because of the pressure ridges near 4k and from about 7k to 10k. In addition, the rounded surface is not completely smooth and the bump near the bottom should not be there with a RTM.

I was recently disappointed to hear from Mike Diamond who just examined the coin I featured in my paper as having likely RTM. He said "Upon examination under high magnification, a (sic) was able to detect a very subtle, very diffuse pressure ridge around each circular pit." I am waiting for him to return the coin now and plan an attempt to see what he is talking about. The marks (there were 2 of them on my coin) must have been subtle indeed, because he also said that they were too subtle to capture digital images!

I am not going to give up the search even though I think that my chances of winning the Lottery would be better than finding a RTM!!

I have established a couple of data bits about RTM
The mint scraps all planchets which have been tested, so it would be less likely one would escape and go into production.
The fact that they scrap the tested planchets illustrates their determination that, depending on the orientation of the planchet in the striking chamber, the RTM could survive the pressure of the strike.
Were dies to have a RTM on the face of the die, the coin struck would have a raised bump. However this cannot happen, because the dies are tested on the neck of the die and not the face.

Yes this rockwell deal is a bugger..sense I found this penny ive been reading more and more about it as years went by..back in2014 there wasnt much on it..thanx to the people looking into this more is being cleared up..hopefully someday they can somehow test the testmarked penny..mine does have a bump bottom ridge but in its defense it devoloped..its a plate blister..may not beleave me..maynot be a test mark..but like you prolly feel about your coin..mine brought me on this quest and if not for the spot id of never known about testmarks..and wen I pulled it in 2014....first thing I said was...it has to be some kinda test mark..id just gone through 2 full boxes of all 2014..i was upset the bank gave me.. I'm also in contact with coneca about mine..they will most likely say its not..i will let you know what they say

Thank you for posting these. They appear to be damage to the coin. The pressure ridge around the depressions is a primary diagnostic for damage.

This 1980-D Nickel appears to be damaged and not a test mark.