Ross-Simons - 1.00 ct. t. w. Black Diamond Ring in Sterling Silver. Size 6. When you feel like adding a little bit of edge, try this all-black ring! Studded with shiny 1.00 ct. t. w. round brilliant-cut black diamonds and completed with a black rhodium finish over sterling silver, the band serves a unique monochrome look. 1/8" wide. Black diamond ring. Diamond birthstones are the perfect gift for April birthdays.