Jade is an interesting Shadow, recently discovered and explored by Princess Kanna of Ember and Lian, daughter of Wasyuu. At first glance, it appears to be your typical fantasy-world shadow: small kingdoms and cities spread across the two known inhabited continents, with lots of unexplored mysterious territory between them. Although the majority of the population is human, there is also a sizeable elf and dwarf population, as well as several other lesser races. Territorial disputes are usually settled with contests or tournaments, not wars, and there is a relatively modern judicial / prison system. Although the common technology level is late medival, some effort has been put into making sure the towns and citadels are hygenic, courtesy of magic and careful plumbing.
However, one of the things that make Jade stand out among fantasy shadows is that the natives of Jade emigrated to the pristene world long ago from another shadow, one that contains its own Earth. The second is that high technologies (energy weapons, force fields, stardrives, etc) work on Jade, and for good reason. Jade was originally built by a shadow-travelling race known as the Nomad Artifacers, who fled some disaster elsewhere in shadow. They created Jade as a refuge, but then fled before they could settle the planet and pocket universe they had created.
Jade has two shadows associated with it:
"Earth-Realm" is very much like baseline Shadow Earth, save for the existance of several spacefaring races which are not known to the general public. Earth-Realm also has a higher concentration of odd archeological sites than would be expected for a late-twentieth / early-twenty-first century Earth shadow. Its technological and magical levels are the same as Jade, however Earth-Realm is primarily technologically focussed. On Earth-Realm, mages and witches and the supernatural are much harder to find, though they do exist.
The second Shadow is known as "The Retreat", a pocket shadow created by the mages and dragons of Earth-Realm during the twilight of the Age of Magic. The Retreat was designed as a refuge for all the magical creatures and races to live in while mankind embraced the ways of technology. There is not much shadow-travel between The Retreat and Earth-Realm, though it is possible in rare cases. Trade is much more common between The Retreat and Jade, and many members of the Edge Guard train there.
The time differentials between Jade, Earth-Realm, and the Retreat remain constant with each other, no matter how much Jade's changes with respect to Amber.