Art Nouveau Butterfly on Super Long Chain by: John A
Hi Adam Are you sure that the original length of the chain was 10 feet?That's around 3 meters!
A three meters 18 k gold sold chain is not common, and will be difficult to associate with any specific Era, especially if the pendant was added later. What's the weight of the chain? Antique Muff chains are long chains. As for the pendant, the butterfly is a motif that can be associated with Art Nouveau era which was around the 1910 - 1920
It will help if you could identify the type of metal, and the stones in the pendant, particularly for appraisal purposes. The weight of the chain will also be important.