This is a heavy wide sterling silver ring band with a square-cut pink gemstone. I do not know for sure what kind of stone this is, but I suspect it is pink topaz because my mother-in-law's birthstone was topaz and she collected a considerable quantity of topaz jewelry. (This is from her estate, and is at least 50 years old – probably older.) This ring may be worn as either a regular woman's ring or a man's pinkie ring because it has such a unisex style. Either way, it is small - approximately a size 5-3/8, (any jeweler can re-size it to fit if you need a larger or smaller size). With a bit of polish, this will make a very nice vintage addition to your jewelry box.
Please note - this is NOT a "tension set" ring. This is much older, estate jewelry - tension settings were not invented until 1960.