Yes, You Can Cut a microSIM Into the nanoSIM Size (Video)
When many phones switched to the smaller microSIM standard, many found it easy to cut their SIM down the smaller size, either with a razor blade or a special tool. With nanoSIM making its debut on the iPhone 5, does the same process apply? The answer is yes, and here is proof. In fact, the nanoSIM is just a microSIM with no plastic around the edges. Not only will you need a sharp razor blad and a straight edge to guide you, but you’ll also need some 180 grit-or-higher sand paper to slightly reduce the thickness of the resulting nanoSIM.
And if you fear that you might one day want to go back to microSIM, you can always buy a converting adapter.