Revision Emax crowns turning gray after being cemented with Block-out. What is the protocol to block out dental shade?

Revision emax crowns, first crowns were turning blue due to micro-leakage, these ones that were just cemented are starting to turn gray. The cement used was called Block-out. I have researched all night about different cements on Emax crowns and not one site recommends block-out which is recommended particularly for lumineers. I feel so depressed as to what I should do now...what is the protocol to block out any dental shade in Emax crowns? I am desperate!!