An extremely rare 77.77-carat yellow diamond is expected to fetch up to US$7.5 million when it goes up for auction in early April. The stone is one of the world’s rarest diamonds according to Sotheby’s Hong Kong Deputy Head of Jewelry, Terry Chu. “Only when a diamond, which has color and the color saturation is strong enough to call vivid, actually it’s always been rarer. And then don’t forget yellow diamond is rare, but when […]