A mystery to the western world, luminous pearls are legendary in China, and people go to great lengths for a chance to even touch one of them. The largest luminous pearl has just been placed on display, in China’s Hainan province.

Very little is known about the giant green pearls of China. The few who actually have heard of these remarkable jewels refer to them as “Yemengzhu” and praise them to be rarities that bring good luck. They have been a part of Chinese legends for centuries, and people there believe that just touching them can bring great fortune and prosperity. But this kind of myths are all to common in a traditional country like China, and what makes Yemengzhu special has little to do with local lore.

Luminous pearls are wonders of the mineral world that shine in the dark without the help of ultraviolet light. This kind of Fluorite is so rare that western geology don’t even recognize its existence, and the Chinese only discovered the first one in 1982, at a Tungsten mine, in Guangdong. Since then, bigger and bigger deposits were discovered, and the largest one yet weighs 6 tons and is 1.6 meters in diameter. When it was discovered, it had an irregular shape, but was ground in the form of a sphere. The process took three years to complete, because of its tough nature, comparable to the finest grade of diamonds.

The largest luminous pearl is currently exhibited in Wenchang, China’s Hainan province, and has been appraised at 2.2 billion yuan ($331 million).

Photos via China News and China Daily