DALLAS, TX.- A spectacular Fancy Blue-Gray Diamond, Diamond, Platinum Ring could bring $350,000 or more when it crosses the block in Heritage Auctions' Spring Fine Jewelry Auction May 3.

"Blue diamonds are very, very rare," said Jill Burgum, Senior Director of Fine Jewelry at Heritage Auctions. "The color is impacted by the presence of boron in the lattice of the stone, which is formed extremely deep within the earth's surface. It is rare to mine a blue diamond, let alone one with such distinct color, and this is a breathtaking example."

The ring features a pear-shaped fancy blue-gray diamond weighing 1.38 carats nestled between pear-shaped diamonds weighing a combined 1.41 carats, all set in platinum.

"Not only is the blue-gray diamond absolutely magnificent, but the stones on each side are D color, internally flawless," Burgum said. "For someone looking for perfect stones, this ring fits the bill."

The ring is one of two blue diamond lots in the auction, which also includes a Fancy Blue Diamond, Diamond, Platinum Ring (estimate: $30,000-50,000). It features an oval-shaped fancy blue diamond weighing 0.73 carat, flanked by full-cut diamonds weighing a total of approximately 0.30 carat, set in platinum.