We inherited an antique Blue Willow platter from husbands gr gr grandmother. She brought it over from Norway in 1862 to US. She was married in 1810. I can not find this exact mark anywhere. Wondering who the maker is and approximate age. The back has a blue stamp of a large crown and a ribbon below with words Iron Stone China, and an R underneath. Also a number 12 impressed on the back. I cant figure out how to get a picture on here. Thank you.