10K yellow gold cocktail ring. Features 5 blue/purple tourmaline marquise cut gemstones in various sizes. 
This was tested using the Presidium Gem Tester II and it the needle fell in the garnet/tourmaline/iolite section. Likely purchased from the Home Shopping Network (HSN).

Size: 5.5
Marked: Marked A inside an octagon shape with a diamond shape and 10K. 
Total weight: approximately 3.6 grams
Condition: Pre-owned.