Hidden Gems: Why the Most Interesting Stones Aren’t Always the Most Famous

When the 5.51-carat Ocean Dream diamond sold for $17.3 million at Christie's Geneva in May of this year, nearly doubling its low estimate, it set the auction room alight. Neither wholly blue nor wholly green, the stone's elusive vivid blue-green colour serves as a fascinating example of a gemstone that resists straightforward categorisation.

For decades, the gemstones that have come to define rarity have usually been those with hues that are immediately recognisable and readily described, from the saturated red of a Burmese ruby and the intense green of a Colombian emerald to the velvety blue of a Sri Lankan sapphire. These stones, which for centuries have represented the pinnacle of gemstone desirability, remain among the most sought-after in the world and continue to command extraordinary prices.