Diamonds have become the choice for investors who are into portable, tangible wealth. Auction after auction, record-breaking sales of shiny, hard assets are heating up.

The next supersized rock expected to set a new world record is not your average rock, it's a rare orange diamond called "The Orange."

Pure orange diamonds, also named "fire diamonds" are exceptionally rare. "The Orange" is a mega-diamond at almost 15 carats, making it the biggest of all fancy vivid orange diamonds to ever grace an auction block.

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"This will become already a new world record per carat and for any orange diamond. Then, it's a question of how big a world record it will create," Rahul Kadakia, head of jewelry at Christie's Americas tells CNBC. To date, there have only been three fancy vivid orange diamonds sold at auction, all less than 6 carats.

"The Orange" is up for grabs at Christie's on Nov. 12 in Geneva, where the auction house expects it will fetch $17 million to $20 million.

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Kadakia thinks investors are making a safe bet on hard assets: "If you want to buy something ... that is eventually going to keep going up because there's only so much of it around, a diamond is your investment. Over the last 10 years, [diamonds] have gone up 300 percent. I don't think any other asset class has done that."

Update: 'The Orange' mega-diamond sold on Nov. 12, 2013 for a whopping $35.5 million dollars; when you break down the cost by size - about $2.4 million per carat.

—By CNBC's Erica Emmich. Follow her on Twitter and Instagram: @MegaMoneyGal.

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