The Portable Antiquities Scheme has published an online guide to buckles - Roman to eighteenth-century.
The differing forms of late Roman and early Anglo-Saxon belt buckles have provided much material for discussion in recent decades, with some forms characteristic of (eg.) late antique administrators and military men (women too?), and with (eg.) triangular buckle plates from prestigious Anglo-Saxon burials.
This is a basic guide and guidance on terms and references to standard works are given.
Finds Recording Guides - Buckles