This large rectangular buckle is suitable for a heavy belt just under 1.5 inches wide. It weighs over 60 g and so is really chunky. It has large featured hallmarks. I don't fit the leather, but see here for details of a company that can.
This is a small buckle suitable for a belt 15mm wide. It weighs 8g and is fully UK hallmarked
£55
This buckle is cast in a cuttlefish bone which gives it a unique surface patterning. It weighs just under 30g and is fully hallmarked. The buckle would take 30mm leather. I don't fit the leather, but see here for details of a company that can.