A white or cream subway tile.

I think glass tile would be beautiful as well!

After reading the comments I'm thinking about a split face travertine (light) tile backsplash?!?

If it helps your thought process, enclosed is a Rainforest Green shower seat with some beautiful tile (I can't remember what it's called) to enhance the look. Perhaps you could go this route.

I like the idea of a neutral colored glass subway tile...and agree with other comments stating let the granite be the star of the show! Something like this would work nicely (see pic). It is by Puccini-Florida series-color: Daytona Beach. You could also use the granite as the backsplash as well... it makes for a really seamless look...but it's not for everyone. I find people either love that idea...or hate it!! I put a photo of the suggested glass tile and a room scene that uses a matching granite for backsplash so you can see how it looks. Good Luck! Would love to see what you select!!

Neutrals & greens would be appropriate. Here are some samples with the granite. All of these backsplashes are from Lowe's web site.

Bonjour
What about back painted glass.

since the overall green has a lot of light yellow tones, I'd either go with granite tiles to match, (excluding the red parts) or the yellow green subway tiles...just make sure that gorgeous slab is star of the show, with no sink or cooktop cut into it...! Just use it on the island . we used a slab on the bar & surround the undercounted sink...but (to save money yet get the same look) used granite tiles to match for side counters & all backslashes...everyone seems to love it...!!

LOVE the glass tile color: Daytona Beach suggested by Timeless Interiors! You can see how nice it looks together when they are close together. Beautiful marble.