I am not sure if these are collar buttons or could be used on a thin woman's cuff as a link. They are taille d'epargne in decoration in which engraved lines in the metal base are filled in with enamel without variation in the depth of the line and in and are approximately ½" in diameter. Check out the wonderful design in these antique links from the 1880's. There is wear on the under button as you can see in the pictures.
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