The chain measures about 16 and 1/2 inches long, from end to end, and should fit at roughly 16 and 3/8 inches long, closed. The serpentine chain is approximately 1.5 millimeters, or just under about 1/16 of an inch, wide. Stamped on the both end caps, "925", and, "Italy", unsigned. Stamped again on the lobster claw clasp, "925".
The pendant measures approximately 3/4 of an inch, or about 19.05 millimeters, in diameter, by about 3/16 of an inch, or approximately 4.7625 millimeters, thick. (Included is a US Quarter in the photographs, for the measurement-challenged and ruler-averse.) I couldn't find any separate markings on the pendant.
Combined weight is approximately 5 grams, which includes the stone weight, of course.
This necklace is in very good vintage condition. No damaged or missing stones. The chain has no kinks, just one very slight bend near the clasp, and the lobster claw clasp works well and holds securely. There may be the expected light surface scratches to the silver from normal wear. Hand polished, but may have missed some tarnish.
A very pretty, classy and versatile, vintage Italian Sterling silver open circle pendant necklace. Lots of sparkle in an understated, elegant style.