When you are searching for information on dishware, you should include several things in your description. Include color and backstamp information. Does the marking on the back show the word "ocean" over a crown with a central cross? If so, that is a very pretty piece.
You can valuate your platter on several sites. Try Kovels, Replacements, or Worthpoint. You can also sold prices on ebay.
Remember that European dishware that feature European scenes like windmills will be more expensive than those made in Asia. Windmill patterns do not seem as popular as they once were. Even plates with windmill patters made by Delft and Royal Copenhagen are not as expensive as other patterns.