Thanks, both of you, The Greyish ones have the slight tint of blue which is stronger in some areas than others. They are much more translucent and show the opalescence better but I think there could be a number of reasons for it from different runs to the start of the blue running low. Everything is the same except the strength of the blue. I thought I had enough of them until I started finding the varying color strengths.
The three up front seem to be a different marble, with a possible exception for the first one, maybe same but older. That one goes near clear backlit.