I am putting granite tile on a kitchen countertop and the tiles have turned very dark. I assume that it is the water from the mortar coming through the tile and it just needs to dry out, but how do I speed up the process? The tiles have not been sealed or grouted yet.

Any thoughts?
Thanks

You cannot speed up the process of drying. If it drys to fast the strength of the thinset will weaken. Did you use the thin set that the granite supplier said to use?
Also until this drys out you should not seal this product as it will not seep into the pores of the tile properly.
Keeping the AC on so the air is dryer in the home will aid in the evaporation process however and not so much as it would effect the bond strength.