White Opal or Crystal Opal?

Lots of confusion about white opal I think. You'd think not as white is white! However the white opal base out of which the opal fire flashes and dances and winks and blinks at you is usually called milk opal. Then the milk gets muddier. Some opal is too milky to be a crystal opal but not milky enough for the milk classification. Also Crystal opal fetches a higher price per carat so many vendors muddy the thinking by calling what is no really crystal crystal. Of course there is semi crystal as a term. However, I have always liked what the miners of Lightning Ridge Australia call that which is not black opal...they call it light opal! A broader category eh? If you were befuddled by the subtle differences I doubt this cleared it up for you but at least you dont feel alone.