Lady's 18K White Gold Diamond Antique Brooch / Pin. Measurment: 22mm x 68mm Contains: Two Hundred Sixty-One Natural Round Brilliant Cut Diamonds. Weight Approx: 3.00cttw, Color: G-H, Clarity: VS / SI. You are viewing a rare and unique antique diamond brooch, handmade in 18K white gold. This amazing creation contains three carats of round brilliant cut diamonds. It is a really chic piece, especially if you are going to a formal affair.