This is a pretty good image of a rose cut diamond. The ring itself is a reproduction, but the diamonds were, in all likelyhood, cut a very long time ago, and look the way most of the world's cultivated diamonds looked until about 100 years ago.
Georgian diamond cluster ring, circa 1830 at Berganza Ltd.
This traditional style diamond cluster ring, most likely of mid-century vintage, sparkles mightily with eight full-cut diamonds surrounding a carat round brilliant-cut center. The bright-white diamonds are set in platinum atop an 18 karat yellow gold