Well that explains it. I tried checking Sapphire units in harem's wiki but it was empty.
I was holding onto them to maybe use in place of my Black Spirits in rare cases but seeing as I don't get that many of them I have been reluctant to use them. May hold onto them myself and see if sapphire units do make there way to nutaku. I do get other black spirit's so it is no real issue not using them.