Talk:Skill Reinforcement Items/@comment-26287946-20160218193811/@comment-556400-20160219010031

Your best bet for secret gems is probably to do the 30-40 AP training field quests (Daily Event Quests: Chaldea Gate). When I was farming Phoenix Plumes in Okeanos, I would very rarely get red gems, so I can't imagine how rare it would be to get secret gems from normal free quests.