sterling 925/1000 mark Heart Padlock charm?

[antiques4ever]

Hello!
Need help identifying the mark Sterling 925/1000 on a repousse heart padlock with working key. I believe it is Victorian but Im not sure what company marked their items 925/1000 sterling. Unger brothers I heard mark some of their items 925/1000 but I dont see their makers mark. No makers mark just Sterling 925/1000.
Thanks!