Pearls have long symbolized power, wisdom, and wealth. The only gem created by a living being, pearls occupy a special place in our hearts. The product of an oyster reacting to a grain of sand or other foreign substance, the pearl forms around the irritant with a protective substance known as nacre. It’s hard to believe that such a thing of beauty could have such a humble origin. At the same time, it is not surprising that such a unique object is known as the Queen of Gems. Pearls were once incredibly rare and thus reserved for the super-rich.

But after the process of culturing pearls was invented about a hundred years ago, pearls became more affordable for the general population. Because pearls are made differently from other gemstones, they have their own unique set of criteria for judging quality. You’ve probably heard of the four Cs for diamonds (cut, color, carat, and clarity). When it comes to pearls, whether natural or cultured, their value is based on seven factors: size, shape, color, luster, nacre quality, surface quality, and, in the case of strands, bracelets, or pearl rings with multiple pearls, how well the pearls are matched. That said, every pearl is unique, and cannot be judged by using a simple checklist or mathematical scale. Special characteristics, even a jewel’s history, also factor into its valuation. Because of this, the most precious pearls aren’t necessarily the ones you’d expect. Read on to learn about t...