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Just a theory. But perhaps those Jade Armor used jade from the Jade Sea. You can't make that large amount of Jade Armors without an insane amount of jade supply. I don't see Kryta having that much jade underground.
Perhaps someone in the Jade Sea was helping the Mursaats. Or the Mursaats have a secret operation in the Jade Sea.
The Jade Sea is greenish (jade); the Jade constructs are purplish (same color as their structures). I see no connection.
Jade Cloaks are of the same color as the statues found in Riverside Province and there are not as many as the jade armors. I also highly doubt that the Jade Sea is the sole source of jade. Likewise, the Jade Cloaks are of a different color green than the jade blocks pulled from the Jade Sea.
Also keep in mind that the EN manual states that the Echovald and the Jade Sea are de-petrifying. The sea is returning, albeit slowly, to water.
I'm also going to add a few things:
Thanks to the fan-day, we know that (part of) the beginning of WoC will deal directly with the Ministry of Purity and helping them clean out the Afflicted.