I was thinking of buying a Sigma Metalytics PMV. I'm a little paranoid about fakes, especially those hard to tell ones which can even fool experts. Researching this machine I see one of the setting is for, 90% silver, pre 1945. While I imagine it works well on coins like the Morgans and Trade Dollars since they were struck at .900 silver. But what of the older silver coins. The dollars from 1795-1804 were .8924 silver. Would these have an accurate reading on the Sigma? Anyone use a Sigma on early US silver coins? I would like to get one, but if it doesn't work on my older coins, I'm not going to bother.
https://www.sigmametalytics.com/uploads/PDFNew/PMV_PRO _Specifications.pdf If you notice, they differentiate among three different purities of 90% I seem to recall they used to discuss custom measurements - you would probably need to measure the value for a bunch of known-good coins to have them program the device. Or else compare the numeric value to your known-good. Or you could just call the company and ask the horse.
The pro version seems like more what I'm looking for. The pro has more settings which would be helpful to me. Thank for your time to answer my question.