The metamorphic belts that were submitted to very high pressure, above 2.8 Gpa, evidenced by presence of coesite and/or diamond, are called ultra-high pressure (UHP) metamorphic belts. Such a metamorphic belt is firstly found at Dora Maria, Europian Alps, and up to today, more than twenty belts have been reported. The UHP belts are formed during continental collision tectonic events. Retrograde stage metamorphism of the UHP results barrovian metamorphic belts of classic model.