Please expand on your question. Techniques? Caulk to use? What are you trying to do?

Clear silicone

The sink has a marble counter with a marble back splash. There is a small space between the two marbles and I would like to caulk it, but my wife does not want to see the caulk. I plan on using GE Silicon II (clear).

Reread post 3, cut the tip as fine as you can, wipe the seam you lay out quickly with a wet finger.

I thought I posted this but-Put a thin edge of masking tape just above and below the joint. Thin bead of Silicone in the joint, wipe off with wet finger as Bob suggests, let set for 2-3 minutes and then peel off the tape. Makes a nearly invisible thin joint. Trim with an exactonife if needed.

Some caulk that has silicone in it is water based. Pure silicone is not. Acetone is the solvent for silicone.