You could consider painted glass backsplash for the whole area above the range. The caveat being that the current tiles above the range need to be cut out neatly to avoid jagged ends.

http://www.houzz.com/painted-glass-backsplash

Beautiful hood. IMO, close always looks like a miss. You could keep looking for a matching stone, dont try to match by name. Take one of your tiles with you. You could also remove the tile in the stove backsplash space and reinstall it intermixed with something new in a pattern, use it to frame a new insert, or just go with all of a new, not necessarily high contrast, tile or even a stainless sheet.

With your fridge, stove, and DW visible in the pic, you're talking about a small area of backsplash. I'd just replace it with something new.

You could do a stainless steel just behind the range, maybe even with a shelf, like this:

Or you could put a cap on the existing tile and just paint above it to match the cabs.

You could also put a shelf there, maybe 6 or 8 inches deep, and paint above it.

I would just paint it and if the difference bothers you, put a decorative platter of some sort. Or put in a glass or stainless steel shelf at the partition. Beautiful Hood!

I will soon be having the same problem. We are doing stainless behind our range. I think it would look nice in your case, or even just a shelf like others suggested.