The lump of dark-green nephrite has an exciting story behind it. An inscription found on the slab says it originates from South Siberia. The sample was discovered in the mid-19th century by Grigory Permikin, a geologist who had been studying Russian deposits of nephrite. That large piece of rock was later presented to Michael Romanov, son of the Russian Emperor Nicholas I. What happened to the stone afterwards remains surprisingly unclear.
The large block of a green-coloured mineral was rediscovered 75 years later by a plumber, who was working down at the basement of the Catholic Church of St Catherine, in St. Petersburg.
Nephrite possesses some unique properties. Due to its unusual structure, it is twice as hard as steel. Besides, it is valued for its musicality. A soft and melodic sound can be heard if one would hit the stone. It is believed Confucius himself was fond of listening to the sound of nephrite plates while meditating.