18ct Gold, Aquamarine & Diamond Cluster Ring (401 O) The Antique Vintage Aquamarine and Diamond Cluster Ring For Sale at 1stDibs 18ct Gold, Aquamarine & Diamond Cluster Ring (401 O) The Antique Aquamarine and Diamond Cluster Ring in 18ct White Gold Rings Jewellery. A fine vintage cluster ring centred with a deep blue aquamarine, measuring approximately 8mm and estimated at 2 carats, securely claw set. Surrounding the centre stone is an outer halo of twelve brilliant cut white diamonds, each measuring approximately 2mm, with a combined estimated total of 0. 36 carats. The diamonds are assessed as colour HI and clarity SI. The head of the ring measures 12. 7mm in diameter with a depth of 5. 8mm, and the ring weighs 5. 3 grams. The ring tests as 18 carat white gold and dates to the 1960s to early 1970s, from just before hallmarks became a legal requirement. Ring size: MFree resizing available.