Delft brooch

The tube hinge with short pin has thrown me with this, just trying to figure out the age of it. The filigree setting is unmarked and tests as 800 silver or thereabouts (my test went brown). The clasp is marked with initials CW with possibly something beside it too small to make out and I can't see any other marks anywhere, pin is not silver. Help?

 

Small Dutch filigree items often weren't marked because of the low weight. It is most likely to be .833 silver and the early years of the 20th century.

 

Thank you AJ