My kitchen has this polished granite-like backsplash. There is no apparent caulk where the backsplash meets the wall. I was thinking of applying silicone caulk at this joint to prevent water from getting behind the sink.

Is there any reason to -not- to do this? Or is there another/better way to seal this gap?

Attached is a piccie that (hopefully) shows what I mean. The gap ranges from 0 to up to perhaps a 16th" at it's most bowed.