here's some partial info:
the dates for the GDR, "German Democratic Republic" aka East Germany, are from about 1949 - 1990. My sketch of your description didn't allow me to find the actual maker. But with apologies in advance to my German friend, Chris Simon-Marshall, Echt Kobalt seems to translate to "genuine Kobalt (Cobalt).
May I suggest that you go to Chris' site:
www.porcelainmarksa ndmore.firmitas.deand with a picture or sketch, e-mail him? He is a true expert on all Germany related marks. Value? well, without knowing the exact company, these beautiful items appear to be valued from minimum $10 to $25 ish. Of course, the specific maker if known, could possibly alter that value.
Best wishes on your continued search, KB