I can't take a call until this evening, but I'd be happy to help if you still need it then. I refinish more black granite than I care to. If you need to talk now, I'm available by email.
StoneRefinisher@Gmail.com
Black is one of the easiest, the problem is you rarely come across true black anymore. There are variables to consider. We buy Indian Premium Black, which is the standard for quality Black Absolute these days. You want to make sure of two things before you touch it: It's not going to etch easily, and it's not dyed. The dye part is more important than the etching. You can scrub the top with a rag soaked in acetone, this will usually let you know whether or not it's been dyed, as there will be black on the rag.
Black Absolute and Black
Galaxy are VERY soft as far as granites go. They are very dense, but not hard. It's easy to cut too much into it, so be careful.