The ring is approximately a size 6 and 1/2, but may be a 7, if the flattened band were to be re-rounded. The face of the ring measures approximately 11/16 of an inch, or about 17.46 millimeters, high, with the decorated portion measuring approximately 13/16 of an inch, or about 20.6375 millimeters, wide, and projects about 5/16 of an inch from the finger. The band is just over approximately 1/16 of an inch, or about 2 millimeters wide. (Included you'll see a US Quarter in the photographs, for the measurement-challenged and ruler-averse.) It is marked inside, "925", and signed in script, "P.D.". Weight is approximately 5.1 grams, which includes the stone weight, of course.
This is a vintage piece, which has been worn and enjoyed. There will be the expected surface scratches and tiny dings in the silver from normal wear. The ring is no longer round and true, with the band flattened in back, and it may have begun life as a size 7. I saw no damage to the stone. Hand polished, but there will still be areas of missed tarnish.
A very pretty, bold and detailed vintage Sterling silver and black onyx ring. Strong styling and great color contrast.