These are just lovely, an antique or very early vintage pair of sterling cuff-links, with a beautifully engraved portrait of a hunting dog, which has then been overlaid with a soft bluish gray enamel to form a guilloche finish.
The details of the dog are extremely well observed, fine and well executed, the cuff-links have been marked with a makers punch, but it is somewhat worn and I found it impossible to read, but these are by a high quality maker. I estimate the cuff links date to the early 1900's, they are in good order for the age, there is some chipping and flaking and one fine crack to the enamel. I have photographed the cuff-links at high magnification, that shows the condition in great detail, at normal scale the wear is at all noticeable, and the overall effect is very fine and old.
The small plate on the opposite end of the cuff link has been monogrammed D B C, this is nicely done in italics, it could be removed by a good jeweler, but personally I would leave as is, as part of the history. The engraved part of the links measures 11/16" long, the smaller disc is 6/16".
These are beautiful antique cuff-links with a very desirable subject as the focus of their design, they would be a wonderful gift, or a fine addition to a collection.