Unusual gilt and banded agate watch chain with matching key c1850

This is a pocket watch chain which is made up of a very fine gilt chain and links. 

This chain supports 4 tubes of white and black banded agate. These are separated by 3 balls of black and white banded agate. At one end is the dog clip and the other end the gilt T bar. Hanging from this is a large black and white banded agate fob and then a gilt and black and white banded agate watch key. The chain measures 200mm from the T bar to the dog clip and is in 95% mint condition – considering the fragility of the watch chain, fobs and keys, it is in remarkable condition but one gilt flower motif is missing from the central agate ball, there is a tiny chip on the fob and the key has minor wear.