This is actually the hardcoat anodizing, not nickel plated.
I have the same one and could not recall the details of it.
Answer from David at OneDrop last year in response to the picture of mine I sent:
"That looks like the hardcoat anodizing we did on those. Very cool
finish and one we didn’t do very often at all.
Cheers,
David"
Here is an example of a Nickel Coated Kuntosh for comparison: