Message #52013

[Fiveroosters aka clayandbrush]

Dear Rube,
Yes it is decorated in underglaze cobalt blue. Just for the report, if it was decorated in cobalt blue and then not covered by the glaze, the decoration would turn out black instead of blue.
I am unsure about the date of your bottle. The appearance of the foot is that of recent bottles, and about the thin body, I am suspecting that it is slip casted.
You could inspect the inside of the bottle with a light. If the inside is very uniform and you do not see joint lines, like for example between the body and the base, then it is more probably slip casted and hence not that old. 
I have the feeling that there are appearing new bottles on the market which are very well decorated, like your one, if it turns out to be modern.
Let’s hear for the opinion of other members.
Kind regards
Giovanni