Yep. I'm on my second space black watch (S0 -> S3). The first one, not a mark after 2+ years of use. Sure, you baby it the first few months, but after that I got over it...and it was just a watch. Doing reno's, landscaping, you name it. It got beaten on, dinged off of door jams, etc, etc. Not a scratch anywhere on it - including the sapphire lens.
Really wish Apple would get us Sapphire for the front lens of the iPhone....maybe one day.
I'm looking forward to the interview where one of the Apple execs spills the beans on what they used for the space grey's steel border. Maybe it'll be Jony. Doesn't matter. Just hope it's almost as hard as the DLC....if not the same hardness.

(if the latter, you'd have to let someone scratch it with a diamond ring....or drag it along some shiny concrete at a resort - shiny concrete often has particulates approaching diamond in hardness).