If you can catch it on a fingernail chances are it's too deep to sand and buff out. It can be tried and maybe to some degree reduced but to completely remove a scratch deep enough to feel with your nail is dicey.
Worth a try but it may mean breaking through the clear and then it's time to re-paint. Go to the shop you have a good relationship with and ask them to try.
I got such a scratch, caused by a climbing cat, out of a black 05' Expedition today. Sometimes you win.
Good luck.