A little off the "stigmata" topic, but maybe useful...
I bought a sheet of almost black (VERY dark bronze) reflective film from a sign/graphics shop & covered all my cladding screw heads with that, then punched out the center with a torx bit & trimmed the edges...gives a nice effect in flash fotoz & at night when hit by lights.
Now that I've seen Marks, I'm thinking of re-doing them all in silver reflective film.
Again, my two cents...