Hey everyone, need some input here. I recently picked up this 1899 peso. Weight is almost bang on and coin is nonmagnetic, but the ping test is odd—right pitch, but the ping sounds hollow (?) and doesn’t ring long enough. However, it also seems a bit thick at 3mm, and this edge is the most concerning part—undoubtedly the reason why the coin is so thick. The grooves seem thicker than a 1909 peso I have, and also seem to be wavy—when looking at the coin horizontally, they appear to undulate. Perhaps a casting seam?
Sharing some more photos. There appear to be denticles in the obverse rim, and the reverse rim seems to be lumpy--almost like a cud? Also note the missing details of the ribbon ("breaks"..?)
If this coin is actually a casting, it is a good one. The thing that has me concerned is the edge which is, IMO, not correct and it appears to be a sandwich.
While not an expert, this period of Mexican coinage is of great interest to me. I believe the thickness "should" be 2.8 mm. I would agree the edge does look 'thick.' For those coins which I have concerns, I do one or both of the following; Specific Gravity Test XRF Scan If you have a scale that goes to .0001 specific gravity testing is fairly reliable and easy. Google the directions. If you live near a college, more likely than not you can locate someone in a chemistry, engineering, or geology lab that has a portable XRF scanner. I made friends with a professor at my local college and he will test coins a few times a year for me in exchange for six pack.
I'd like to see more of the edge. There appears to be a seam of some sort on the one side but not on the other.