Ross-Simons - 8-8.5mm Cultured Pearl, 1.20ct t. w. London Blue Topaz Earrings Over Sterling. An RS exclusive. Luminescence meets boldness in this stunning pair of earrings. Here, 1.20 ct. t. w. emerald-cut London blue topaz suspend beautiful 8-8.5mm cultured freshwater button pearls. Set in polished 18kt yellow gold over sterling silver. Post/clutch, blue topaz and white pearl earrings. Pearl birthstones are the perfect gift for June birthdays.