12-15mm Multicolored Cultured Biwa Pearl, 19.90ct t.w. Pave Diamond Necklace. 36" Our breathtaking necklace is an opera-length strand of 12-15mm multicolored baroque cultured freshwater Biwa pearls in pastel shades, magnificently enhanced by pave diamond beads with an astounding total ct. wt. of 19.90. 18kt yellow gold necklace with black rhodium finish. Pearl birthstones are the perfect gift for June birthdays.