Get a 5 inch diamond core bit, it can be driven from a heavy regular
electric drill, it cuts just the edge with diamond and can goi thru
granite. they are available good used for about 25 bucks or less per
inch, if you need a source e mail me.

with your location its a good investment for future projects and is
useful for things like going thru concrete too.

a buddy had this trouble thats how i know..........

this bit is used for granite countertops