When Old Rose dropped the diamond necklace into the ocean at the end of Titanic, it turns out she was probably just returning it to where it originally came from. Researchers in Australia and Germany have found that many diamonds begin life as sediment on the bottom of the ocean, before being swallowed up by the Earth's mantle and forged into our favorite shiny stones.

   Generally held up as symbols of status, wealth and romance, diamonds may be starting to lose a little of their mystique in recent years, as scientists learn more about them. The gems are far more common than you might think, with a quadrillion tons of diamond newly discovered deep within the Earth, and there's plenty of them floating around out in space. They've been found to contain brand new types of ice and, of course, lab-made diamonds have become virtually indistinguishable from natural ones – to the disdain of the jewelry industry.