Jade is most important in Chinese culture. It is the Stone of Heaven. Even in primitive times it was a rainbow bounty for mankind, who could make sharp axe blades for protection and building without having to go through an Iron Age.
In old China, true jade was valued far above gold or silver. Apart from being rare, beautiful and indestructible (which links it with immortality), it is also of great mystical and spiritual significance.
Jade expresses all human virtues, and if you wish to speak to Heaven you will need a Jade PI-DISC. This is a thick circular piece of jade with a hole bored into its center. Simply hold it to your mouth and speak into it with a suitably devout tone.
Heaven will hear your pleas, and the JADE-EMPEROR himself might answer. Although, knowing how the Chinese Heaven operates, you’re more likely to get into an argument with The Heavenly Official In Charge Of Switchboards.
We don’t quite know how you receive incoming calls. Presumably you hold the PI-DISC to your ear. As such devices are purest Jade, you would need to be as rich as an Emperor to own such a thing. And you never see an Emperor listening to anything like that.
We have several images of PI-DISCs. Downloading a print, cutting it out and attempting to speak through it will not get you through to Heaven. But a cardboard PI-DISC is not without its uses. Any disc with a small hole can be used for cheap star-gazing. Chinese astrologers in imperial times used them to peer at stars and planets using the ‘Pinhole Camera’ technique — still used today for observing eclipses.