14 kt. Solid Gold Blue Trio Stud Earrings. Solid Gold Rainbow Moonstone, London Blue Topaz and Aquamarine. These studs are an icy cluster of moonstone, aquamarine, and London blue topaz, creating the perfect combination of cool-hued gemstones. Product Description: solid 10kt gold; natural 3mm faceted rainbow moonstone; natural 2.8mm rose cut London blue topaz; natural 1.4mm aquamarine