There are two cobalt lightnings that I'm aware of, both pints.  It's been speculated that they were made for the medical community.  I really don't know what the basis of this is other than other jars in deep colors were made unquestionably for the medical community.  It may be and it may not be.  There's really no way to tell for sure.

This is another of those jars which I really wanted but didn't figure that the chance would ever come along when a call came in to see if I wanted it.  I did and paid a substantial sum, but it was probably the only time I'd ever be offered this particular jar so it was either buy or essentially give up on ever owning it.  I'm glad I decided on "buy".