Hello
I have a IAB that was previously housed in an old photo frame. I've just come to remove it and clean it up and was looking for a maker mark - there isn't one.
However, on cleaning it, it appears to be silver (or silver plate) as has polished and tarnish removed. Also, on the front where there is rubbing its possible to see what looks like copper underneath.
I thought the vast majority of IAB were zinc based so wondered whether this is now not a period piece after all?