User blog comment:Nekokokokoko/Slane Theocracy's awareness of Ainz/@comment-26558632-20150920170258/@comment-27008999-20151128152608

Look folks!

We don't know if the crystal was created by with a ritual through the use of Miko priestesses or a legacy of the SGG, so lets just leave it, okay? All we know is that Nigun was entrusted with a crystal worth a 7-8th tier spell.

In my opinion the crystal is not a legacy item of the SGG because they are protected by Zesshi. Slane T. can create crystals of 7 tier based on info on this wiki through the use of rituals.