69-72 PO3 Hub Caps - were these ever really chrome?

[DeadheadNM]

I sent five of what I believed were chrome 3/4t PO3 hubcaps for re-plating. The shop called to tell me the caps were in fact stainless so these were polished instead.

Three of these caps came from a low mileage k20 suburban survivor (see here http://67-72chevytrucks.com/vboard/s...d.php?t=467636 ) and I believe these are original to the truck. Another cap is an original blue bowtie convex example. A thin fridge magnet didn’t stick to any of these including the yellow bowtie example. I have a blue bowtie convex NOS cap and when I look closely it appears to have some “grain” to it so I suspect it’s also stainless not chrome.

Can anyone 1) show me how to confirm a chrome cap apart from a stainless cap and 2) prove there are chrome examples for 69-72 apart from highly polished stainless steel? Anyone have an example of chrome plate peeling from a cap?

Pics attached of before and after polishing.