Reuters/Denis Balibouse The blue diamond, set in a ring, was said to be among the largest known fancy vivid blue diamonds and was the showpiece gem at the Sotheby's jewelry auction.

The Blue Moon — so-called in reference to its rarity, playing off the expression "once in a blue moon" — topped the previous record of $46.2 million.

Previously the owner of a Blue Gem knife turned down an offer of roughly $1.5 million, making it the most expensive Counter-Strike skin in existence (at least in its estimated value).

The Blue Supermoon: A Gem in the Night Sky Wednesday’s full moon, the second in August, was a celestial rarity. It was also bigger and brighter than usual.

The 17.6 carat stone is described as the "largest internally flawless fancy vivid blue gem" to go up for auction. And a Rolex worn by Marlon Brando in Apocalypse Now sold for close to $5 million.

How a Smithsonian Curator Discovered the Hope Diamond’s Many Secrets The storied past of the 45.52-carat sapphire-blue gemstone hails back to the days before the French Revolution ...

An unidentified buyer paid CHF 39,505 million (US$43.8 million) for the pear-shaped Bleu Royal, as the gem is known, placing it among five most expensive fancy blue diamonds sold at auction.

Each month has at least one representative gemstone. Here's what you need to know about September's birthstone.

The world’s largest blue diamond ever to come to auction has sold for 450,925,000 HKD, or $57.5 million. Named “The De Beers Cullinan Blue,” the massive 15.10-carat step-cut gem sold at ...

The 12.03-carat "Blue Moon" Diamond is said to be among the largest known fancy vivid blue diamonds and was the showpiece gem at Wednesday's auction.