Jade, hidden in a stone, is pure. Therefore, the word pu is most suitable for the topic. This word often means that people have connotations and excellent qualities that are difficult for ordinary people to find. Moreover, this word has a long history. There is a saying in Tao Te Ching: San Pu is a device.
The ones mentioned upstairs are all nicknames for jade. How can we say they are natural treasures?
I think the landlord upstairs is too simple. The landlord can't even recognize the words next to these jade characters.