Theory history: Submitted 2013-12-09
In Submachine 0, at the end you are greeted by this message:
Unlike Wisdom Gems in the rest of the series, this gem is green. My theory is that the Gem in Sub 0 is the unique, real, original wisdom gem, and that the Wisdom Gems in the canon series are replicas or weaker versions of it."You have found the ancient gem of wisdom. Wisdom give you the strength to choose your own path"
(Please edit this theory, it is solid, but needs more evidence)