My chips are all pretty worn so don't make a good comparison with your SU chip. I have seen the paul-son metal inlays with clay covering the edges of the inlay. If someone scraped this away, that could account for the different appearance of the surface. You can see something similar if you look closely at the $20 chip surface, although it's somewhat obscured by the layer of fried chicken debris from the Gardena restaurant .

I hadn't noticed the pin-holes in the clay on your chip before. I don't know what could have caused that.