We recently had LEATHERED granite countertops installed. We are waiting for the majority of the kitchen backsplashes to be cut to height in order to fit under existing wall tile, but one piece was installed already. The silicone is so shiny, it sticks out like a sore thumb. I applied some translucent silicone in one spot to experiment and it is not much duller. I can't imagine latex caulk or grout being an option with this application. I have reached out to our granite company, but I would also like to get other opinions.
Wow! Not how I ever installed any backsplash.
I would have applied a small bead of silicone to the bottom edge of the BS, install it on the counter top and push down and hold down until dry (sticks work, weight plates) and scrape off any silicone that squeezed out so all you see is a tiny or no seam. I would not apply it after the splash is installed, it never comes out right.
You can try to remove the excess carefully with a sharp razor blade and slice down between the splash/countertop and silicone very slowly and carefully and remove the excess unsightly silicone.
Tape never works, there will still be a raised edge that you will have to smooth out.
Based on the super straight lines I assume the installer used the tape method but chose to expose a lot of granite rather than targeting just the seam.
Either have them do this or do it yourself after they install everything:
For the existing install the only fix is to remove the silicone and apply it properly.
In addition to the preferred option of only caulking in the crack not on the crack, there's also the option of using colour matched and texture matched caulking.
It's usually used for caulking between grouted tiles and a finishing edge or counter top, but it could also be used where there is an existing gap that needs filling by anything but shiny silicone.
They are far more expensive than regular caulk, but you only apply it to the critical interfaces. It's acrylic based with the endurance of silicone and is anti-mold.
With a wide variety of colours available you can match it to the dominant colour in the granite.
I don't know all the brands, but here's an example that I have used: "Keracaulk S" Sanded Acrylic Caulk 311ml - Ivory