ON the window sill, or AS the window sill?

I have quartzite as my window sills as well. The quartzite is also the blacksplash up to the window ledge - approx 4" of splash. It looks great and is easy to clean. Pictures are online if you google my name + gardenweb. It will give you an idea of the visual.

AS the sill. I’m guessing 4-5 inches deep.

Go for it - it'll look great!

Thanks for all the great suggestions. I’m going to go for it!

we have leathered absolute black countertops and windowsills in the kitchen with a marble looking subway tile blacksplash (around window) we also have it in the master bath above a kohler slipper tub, tub surround is wainscoat that looks good too

My kitchen counter comes right up to the windowsill at the end of the galley. It was at a slightly different height--about 1/4". My countertop guy cut a new windowsill shape from thinner Corian to put on top of the windowsill.

There's caulk at the seam, instead of fusing, because something needs to be able to give a little, since the countertop is horizontal and the wall the window is on is vertical and at a right angle.

I love it.

Visually, it looks very nice and continuous. But windowsills get grubby easily (especially here in NYC, and especially in a kitchen), and it's so easy to clean.