Silver-plated coaster, attributed to International Silver Co. (not authenticated)

This item is a single octagonal metal coaster featuring a circular recessed center and a raised rim with geometric corner facets. The physical characteristics include a silvery metallic finish, likely silver plate over a base metal, displaying significant surface wear, oxidation, tarnish, and scratches. The center of the underside shows a circular maker's mark enclosed in a stamped border containing legible text reading 'IS' inside a rectangle, surrounded by the text 'INTERNATIONAL SILVER CO.' along with a copyright symbol. There is a large area of residue and adhesive staining around the central stamp, suggesting the previous presence of a label or sticker. The overall construction and weight indicators are consistent with mid-20th-century mass-produced tabletop serveware. The owner supplies context describing this as part of a set of six coasters made by the National Silver Company, but the visual evidence of the stamp directly contradicts this specific user-supplied claim by displaying the International Silver Co. mark instead. Therefore, the user-supplied attribution is treated as unverified. The identification in the name rests on the visually legible stamp on the underside, but the item itself remains unauthenticated.

Based on what I can see in the provided photograph, this is an octagonal silver-plated metal coaster displaying an impressed maker's mark on the reverse. The owner describes this piece as part of a set of six from the National Silver Company; however, the underside clearly bears a stamped mark reading 'INTERNATIONAL SILVER CO.' alongside an 'IS' symbol. Because this stamp directly conflicts with the user's notes, the attribution remains an unverified hypothesis. The finish indicates electroplated silver over a base alloy rather than solid silver, with visible surface oxidation, scratches, and adhesive residue. I cannot verify from a photo whether the silver plating has worn through completely to the base metal, nor can I confirm the physical weight or composition; an in-person physical inspection by a tabletop specialist would be needed to test the metal and review the stamping details under magnification. If assumed to be a standard mid-20th-century production piece by International Silver Co., a single coaster of this design and worn condition typically holds nominal decorative value. Complete, polished sets of six to eight similar plated coasters generally realize around $25 to $40 in the secondary market, placing a solitary, uncleaned example in the $10 to $20 range. Should the piece be an unmarked generic reproduction or show heavy plate loss, its value would realistically drop to under $5.