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I bought these from a established member on BS... does the bar on the right look off? There seems to be tool marks near the serial number... I posted this on BS but I couldnt upload the picture right there. I'm computer challenged.
I XRF tested them and they test as silver...

That's from a rotary numbering stamp getting pressed in a little too far. Never seen it on an Engelhard before, I imagine they usually got scrapped if that happened, but that is the correct tool. Somebody faking them would be more likely to have an individual type set and a holder (couple hundred bucks) versus a big rotary stamp (couple thousand bucks). The font/style of the serial number looks correct too. From that photo the "AR" in Engelhard maybe looks a little suspect but I think it's just the lighting and angle. Adam will have a better opinion on that part.

The bar looks like it came loose from the locating fixture and tipped forward as the serial number was stamped.