Just finished transferring my Death Knight over to the PTR and noticed that my red tanking "Regal Dreadstones" have become "Regal Eye of zul's" in turn breaking my meta bonus.
Some gem colors have changed! Hit is now blue. Mastery and Dodge are yellow. Intellect is now red. These simple changes have created a much more diverse matrix of gem cuts.
think those were just examples... (can't find the full list)