Imari plates have been made for centuries, and even still made today. Most of the earlier one's will have marks, They took much pride when making their porcelain items. Most unmarked ones are post 1950's or late mid-century one's these once had paper or foil label, that have look since been washed away. I would also assume that some of even the earlier once may be unmarked but this would be few and far between. One thing to note is most of the earlier pieces the Foot of the plate will be unglazed, and one would also see much wear from age. Overall earlier imari style items are hard to come by, that is earlier century and before. Would love to see a pic of the plate and this may help to determine the age.
