Aquamarine and diamond ring, 1950. This cluster ring is set with a very well-cut aquamarine of excellent sky-blue colour and transparency. Most prominently sourced from Brazil, aquamarine has long been associated with water due to its colour (caused by iron impurities), and examples of a pure, soft blue are particularly prized. The birthstone for March, it was also traditionally thought to be a talisman for sailors, ensuring calm water on their voyages. Set within a border of brilliant-cut diamonds, to a yellow gold mount, this beautiful cluster would make a perfect engagement ring.