Orange diamond to fetch $20 million

The world's largest orange pear diamond is currently being displayed in Hong Kong. The 14.82-carat vivid orange diamond was put on display on Oct. 28 to proceed the upcoming Geneva Magnificent Jewels auction scheduled for Nov. 12.

The diamond

Called "The Orange," the stone is incredibly rare. It was mined from South Africa about 30 years ago, then cut from a crystal weighing over 32 carats. This pear-shaped gem is estimated to fetch $20 million at the Christie's auction.

"Orange is one of the rarest colors. You hardly ever see an orange over three, four carats. This one is over 14 carats so it's of an exceptional size, and we estimate it from between 17-20 million (U.S.) dollars. But as it is pretty much unique, who knows what it will actually fetch," David Warren, Christie's senior international jewelry specialist, Arkansas CBS affiliate THV.

The Gemological Institute of America and Christie's agreed that The Orange is the largest diamond its kind they have come across.

Orange diamonds

White, pink and blue diamonds typically appear at auctions, but orange stones - known as "fire diamonds" - are rare. According to the GIA, colored diamonds are graded more for their intensity than for fire or brilliance. These stones are often described with hue, tone and saturation. Hue refers to the diamond's color - orange in this case - tone is the relative lightness or darkness of the color, and saturation is the depth or strength of the color.

The diamond cut of a fancy stone can impact its color. Mixed cuts intensify the color in yellow gems, for example. As far as clarity goes, fancy diamonds - though valued for color - can have inclusions that influence their value. Gems with inclusions are still given a high value if the color performance is good. However, if an inclusion impacts durability, the value will decrease.

Other notable stones

According to Bloomberg, "The Pumpkin Diamond" was the last orange pear diamond of the same classification to appear at an auction. The 5.54-carat gem fetched $1.3 million at Sotheby's in 1997. Though a rare and exciting piece of gem history, The Pumpkin Diamond does not hold the record. A fancy intense pink stone was auctioned at $45.6 million at Sotheby's in Geneva in 2010. It currently holds the record as the most expensive diamond sold at an auction.

However, a diamond is expected to exceed the fancy pink stone with an estimated $60 million. This second vivid pink diamond will go on sale the day after The Orange.