Beautiful vintage 14K yellow gold oval blue topaz cocktail ring, which features a distinctive split-shoulder filigree setting.  Maker's Mark and Gold Purity CID Mark: The "CID" stamp inside the band stands for Clyde Duneier, Inc., a famous American jewelry manufacturing firm founded in New York in 1910. The company is widely known for producing high-quality gemstone jewelry throughout the mid-to-late 20th century.14KP Mark: The "14KP" stamp stands for 14K Plumb Gold, rather than "plated". "Plumb" is an old jewelry industry term indicating a strict guarantee that the alloy contains exactly or slightly more than 58.33% pure gold, certifying its full, honest 14-karat value.