The Ocean Dream Diamond sold at Christie’s Magnificent Jewels auction in Geneva for $17,300,000 — nearly double the $9.8 million it fetched at the same auction house in 2014. The result is a world record for a blue-green diamond and one of the most compelling demonstrations of natural diamond value appreciation the market has ever produced. In eleven years, the Ocean Dream gained more than $7.5 million in value, an appreciation of approximately 77 percent. For anyone who needs a real-world example of why rare natural color diamonds represent genuine long-term value, look no further than what just happened in Geneva.

Few stones can quicken the pulse of Tom Moses, the Gemological Institute of America’s (GIA) executive vice president and chief research and laboratory officer, who has graded just about every legendary diamond of the last five decades. But the Ocean Dream diamond did.

The breathtaking 5.51 fancy vivid blue-green diamond, cut in a triangular shape, is unlike any other diamond on Earth. “I could spot it from across the room,” said Moses. “I have never seen a natural blue-green diamond of this intensity of color, size, and it is a Type IIa, which certainly makes it a unicorn.”

The only diamond that comes close is the Dresden Green, he says. But even the 42-carat green diamond, also a Type IIa (a category of diamonds that are the most chemically pure), doesn’t come close to the Ocean Dream’s electric color. Until the Ocean Dream, Moses had only seen this shade of blue-green in stones of less than one carat, making this diamond a true natural wonder.

Discovered as an 11.7-carat rough in Central Africa in 2002, the Ocean Dream was purchased by Cora Diamond Corporation in New York. Moses conferred with the company over several months during the high-stakes cutting process, a particularly risky endeavor given the stone’s sensitivity to heat.

“It was a very tense cutting process because it was a gamble,” says Moses about the period more than 20 years ago when the stone was being polished, and that’s what makes his pulse race. The gamble paid off.

When the diamond first appeared at Christie’s Magnificent Jewels sale in May 2014, it fetched $9.8 million. It was a remarkable result at the time and, as today proved, just the beginning of its value story. It was offered in a sculpted rock crystal ring with pavé pink and white diamonds. To this day, it remains the largest fancy vivid blue-green diamond ever graded by the GIA.