So I just got this raw 1874 cc Trade Dollar with one chopmark. I prefer graded trade dollars . This one tested good on the sigma and is pre 1900 90% silver and weight 26.93 grams for a worn dollar seems good. Coin has a little pvc which can be removed but the cc does not look exactly like any I have seen . It does not look altered though. Seller has return privy if unopened which I’m debating sending it back for that reason but otherwise a nice circulated example.
No worries, looks real to me. There are at least 6 different CC mint marks for 1874. Acetone will take care of the PVC.
[QUOTE="COOPER12, post: 8357578, member: ......This one tested good on the sigma and is pre 1900 90% silver and weight 26.93 grams for a worn dollar seems good....[/QUOTE] How were you able to determine that the composition was Pre-1900?
How were you able to determine that the composition was Pre-1900?[/QUOTE] sigma tester said it. Seller sent a pic of it on there since im always questioning ungraded Trade Dollars that I can not see.
sigma tester said it. Seller sent a pic of it on there since im always questioning ungraded Trade Dollars that I can not see.[/QUOTE] A sigma tester only measures the resistivity of a sample and compares it to a programmed "standard". Basically it's a go/no go gage. With all of the compositional variability due to remelting old coinage, and minor impurities in the non silver part, etc, I would think that the error bars on pre 1900 vs post 1900 would be too large to provide a meaningful result. No problem with the 90% silver part, but classifying by century? Seems like a huge stretch. Either Sigma Analytics is making some big claims, or someone is misinterpreting the testing capabilities BTW: None of this is germane to the question in the OP. Just trying to understand this particular statement
A sigma tester only measures the resistivity of a sample and compares it to a programmed "standard". Basically it's a go/no go gage. With all of the compositional variability due to remelting old coinage, and minor impurities in the non silver part, etc, I would think that the error bars on pre 1900 vs post 1900 would be too large to provide a meaningful result. No problem with the 90% silver part, but classifying by century? Seems like a huge stretch. Either Sigma Analytics is making some big claims, or someone is misinterpreting the testing capabilities BTW: None of this is germane to the question in the OP. Just trying to understand this particular statement[/QUOTE] I am not sure how they can tell but I’ve seen it showing this on a few different results from different people testing different dollars.
I am not sure how they can tell but I’ve seen it showing this on a few different results from different people testing different dollars. View attachment 1483331 [/QUOTE] They must have done a heck of a lot of statistical work or are just assuming post 1900 is primarily copper
I've seen the "pre-1900" thing on other images of Sigma results and am curious if anyone has an explanation. Canada switched from .925 silver to .80 in 1920 - what does it read on those?? I'm not aware of any country switching silver content at exactly 1900. Edit: OK, I answered my own question. You select what to test for. This is from their user guide. "5. Select the alloy using the left and right arrow keys. a. Gold- lists the following alloys: Pure .999+, 91.7% 22K bal Cu, 90% bal Cu, American Eagle, Krugerrand, and 98.6%. b. Silver- lists the following alloys: 99.99% Pure, 99.9% Pure, 92.5% Sterling, 90%US pre 1900, 90%US pre 1945, 90% Coin 1960, 96% Britannia, and 80% Canadian. c. Other- lists the following: Platinum, Palladium, Rhodium, Copper, and Calibrator. d. Bullion- lists the following: Silver .9999, Gold .9999, Platinum, and Palladium." In the notes section, it says "Morgan and Trade dollars should be measured on the Silver-90%US pre1900 range. Peace dollars and walking Liberty half dollars should be measured on the Silver-90%US pre1945 range."
I ended up sending it back since by the time it gets graded I would be out of luck if it was not verifiable.
