18ct Gold, Aquamarine & Diamond Cluster Ring (401 O) The Antique Santa Maria Aquamarine Diamond Ring at 1stDibs santa maria aquamarine Vintage Aquamarine and Diamond Cluster Ring For Sale at 1stDibs Aquamarine and Diamond Cluster Ring in 18ct Gold Aquamarine Diamond Gold Cluster Ring at 1stDibs. 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.