Sterling Silver Marcasite Blue Glass Paste Fashion or Cocktail Ring - Size 5.5

Dating to the 1980s or so may I offer this Sterling Silver (hallmarked 925 as pictured with a makers mark I do not recognize) fashion ring featuring an ice blue glass paste surrounded by faceted round marcasites and a lot of "antiqued black". Design at the top of the ring is 9/16" north/south (at the blue stone) and 5/8" x 5/8" (rectangle of marcasites); weight is 5.8 grams. Ring size is 5-1/2. Condition is very nice with no stones missing.