Dan, I have to disagree with you. Blue cased is not a rare or unusual colour, it is a catalogued colour used from around 1957 on a few production patterns and more regularly in the early 60s. I have quite a few items in Blue/cased, but it is possible that some patterns were more popular in ruby or the green cased and there MAY be less of the blue, I don't know it is just speculation on my part that these small bowls are more often seen in Ruby, less so in green and maybe less so in blue. But it does not make them rare and unusual. One Ruby one sold recently on ebay for about £20 if that helps. Regards Emmi