Since you already have the four inch BS, and the wall is nicely painted, you can leave as is.
But if you want to add tile, I would do something similar to the paint color. If I am right verde has caramel speckles and this paint matches those speckles?

I like your black knobs on the white cabs. It's a nice change from all the polished chrome on white.

I'd go with a glossy black tile, either glass or ceramic, so it blends rather than contrasts with the short splash. You could use pops of accent tiles in the peacock colors, maybe in a handmade glass or iridescent tile--something that isn't a solid color since the black field tile would be solid.

I agree with Ellendi -
Another option would be to get glass shelves from Ikea and back paint them - there was a thread awhile ago on some peeps who did this.

I also agree with Ellendi. Your kitchen is lovely as it is. You might run into a problem at the end of your wall if you want to bring the BS around the corner because as I see it there is no 4 inch piece on the end.

LOL Now I want to slap you upside the head for feeding my addiction. I just wanted to look to see if I could find a pretty tile for you and now HAVE to go back and order some for me. NO I do not need more tile. NO I do not need to add more weight to this house. YES I am a glass and tile addict. Do they have some self help group for this?? All joking at you of course. I needed an excuse to go to town.

Seriously there are some really pretty blackish tiles out there. Link below to just some I found while trying not to look. I can not see your granite well enough to match some thing up. I am way too out there for my choices anyway.If you do do black tiles I would go with black grout or very dark gray. White or light grout would be too in your face on this.You want yout tiles to shine at you not the grout lines. You really do not want to take away from your lovely counter.The tiles on mesh are simple to install. Leaning under cabinets to grout and clean up is back breaking. And you will need to have your plugs and switches brought out from their places the thickness of the tiles. I am not sure how hard that is to do because I cheated mine when I did it but I do not recommend it for a professional look.

Some one mentioned painting the back of clear glass. This works just fine just do not get it too thick on the glass or it might want to come loose. I have used oil paints (they take a long time to dry), Acrylic paints, modge podge and glitter, Alcohol inks are really fun too. If possible have your glass pieces already cut to fit before painting because the paint wants to chip when you cut the glass.

Chris

Here is a link that might be useful: Black tiles by the pages.