I was very happy to receive this Azure (cased Sapphire) water bottle. This example has the raised ridge bottom which means that it was made somewhere from 1976 to 1988. I believe that the raised ridge water bottle was made from a mold used for at least the years 1976 to 1988. In any case, Cobalt was introduced in 1990 and it is somewhat possible that this is Cobalt but there is less than a 07% chance of this being cased Cobalt. At this point, Turquoise and Dusty Rose are the only raised ridge bottom water bottle colors that I do not have.