I asked the seller at Morgan Advanced Ceramics - Diamonex products and he told me that it was true DLC.
Here's the pictures of my rist pins DLC coated, end of thread.
I'll be looking next to DLC coat the cam journals and lobes, buckets. Maybe.
What's expensive is the fixture to hold the part inside the DLC coating unit. I've been quote 1000$ for the crank fixture.
I'll ask if I can fab my own fixtures.