Thank you for contacting Mearto with your appraisal inquiry.

It is a lovely antique pendant. Such antique pendants are being offered at auction on a regular basis. Your sterling silver Judy Jack camphor glass pendant set with marcasite and a diamond in the center is very charming. The design of the pendant is typical of the first part of the 1900s. I would date the piece ot have been made around 1900-1910. It appears to be in very good condition with only minor signs of wear and use. The use of materials like sterling silver and marcasite stones was very typical of the particular era and type.

I believe that this lovely pendant would attract the attention of both collectors and dealers if it came up for auction.
The estimate provided is for a well-advertised specialised online jewellery auction, where I believe the pendant has the best chance of realising its fullest potential. However, there is no measurement for the sentimental value you might attach to the pendant. Retail "asking prices" can be higher and vary.

Please let me know if you have any additional questions. I’m happy to help.
Thank you