Le Guide de L’Espresso has been publishing their annual guide to dining in Italy – I Ristoranti d’Italia – since 1978. They also now publish their guide as a mobile app.
They rate restaurants with cappelli symbols – toques or chef’s hats – according to the following scale:
1 cappello good
2 cappelli high quality
3 cappelli great
4 cappelli excellent
5 cappelli the absolute best
You can purchase the 40th anniversary edition of their guide [in Italian] here.