Never seen that before on a non-Roman watch. Frankly, if those hands are original Rolex they have some value as black hands for a 1570 are no longer available from Rolex. Most watchmakers simply paint metal hands when they need a set.
The black markers are rare but the ones I've seen came with ordinary metal hands. I have a 1625 with the "onyx marker" dial. As you can see, ordinary metal hands.
