I suspect this is gold dial which was worked on to produce the desired color which causes this grain. I have the same on a GO watch with gold based dial - very nice!
By: Chronometer (aka yacomino) : November 16th, 2020-11:59
if I take a picture of my dial I see the same grain you have, but it is not visible when I look at the watch myself though. Here is an example from my chronometer ...