Black or white Corian sills go with anything.

I'm limited to granite here, I have a whole range of colors, but I'm focused on
black: https://www.google.com.br/search?q=preto+s%C3%A3o+gabriel

dark green: https://www.google.com.br/search?q=verde+ubatuba

and white: https://www.google.com.br/search?q=branco+itauna+granito

The stuff similar to Corian in Brazil is very expensive, much more than I can spare.

I've had my granite counters as window sills in 2 kitchens now and love them.

Kitchen in old house

New house

This is very nice nhbasket, do the sill on the outside matches the one on the inside? What about the door sills?

Don't match your entire house to the kitchen countertop you happen to have right now.

I don't plan to Marcolo, but I want to match at least the inside window sill above the kitchen sink to the countertop (the outside would still be the same color as the rest of the house).

Is it strange to have a sill with one color on the inside and another on the outside? The window will be blindex glass.

I would treat your sills as part of the house's architecture, separate from the kitchen counter.

Do you have a picture of the kitchen window & counter area, to see if that will look odd with the counter? What are you planning for a backsplash?

This is not a renovation, is a new construction. There are so many details that it is overwhelming...

An elevation or plan view of the area then?