An 18th century Georgian-era cluster ring with tiers of silvery rose cut diamonds. Set in silver-topped prongs in a gold mounting. Probably modified in the 19th century to make the settings open backed and replace the shank.
Note that due to the age of this ring, and style of construction, it wouldn't be well suited to everyday wear.
Currently a size 5 and could be resized in the 4 to 7 range for $75.