The Vintage Wrist Watch Company has dated this piece to the 1920s.
Niello is a black mixture, usually of sulphur, copper, silver, and lead, used as an inlay on engraved or etched metal, especially silver. It is added as a powder or paste, then fired until it melts or at least softens, and flows or is pushed into the engraved lines in the metal.
The chain would sit nicely with either a gold or silver coloured pocket watch.
The Vintage Wrist Watch Company has dated this piece to the 1920s.
Specialists in antique and vintage wrist watches and pocket watches
You can view the stock and full dealer information on the The Vintage Wrist Watch Company Profile Page