Ahhh, with hand hving just received cortisone and/or steroid injections, we meet again!
I think I heard it best said, “the ONLY thing that matters is if the stone speaks to YOU!”
I’m with penumbra though, it’s had some time out of the body of water it was originally in…probably a decent amount of time for that color! That’s not merely “black rock” but rather a blacked 2nd stone. Basically, a microbial crust that has been out of water long enough to have gone from its original color and texture (probably a rather raspy grey or brown), to that nice, smooth black…this doesn’t happen in a season. It’d be rather fortunate (or forced if even possible) if somehow this color of 2nd stone was achieved in 2-4 years!
I’ve come across stones I literally KNOW have been buried in muck for 40 + years, that don’t have THAT nice of color and texture!!!
I’m sure it can be achieved in far less time…just saying, it often takes quite a while if done naturally.
Hope it brings you pleasure!