I've had versions of these in gold, but never in silver!
A classic fancy link and mariner link chain with silver shield like padlock.
 
The four mariner links are engraved with flowers, and those inbetween are linked together in a magical way. 
 
The padlock resembles a shield, the outer edges are beautifully scrolled, and the centre features foliate engraved motifs.  
Cleverly the padlock is not ‘puffy’ but slightly concave, this is intentionally designed to eliminate the risk of denting often seen with ‘puffy’ hollow padlock clasps
 
weighs - 20g
chain length - 7"
padlock measures - 40mm x 25mm
English circa 1840