I recently bought a large 12-sided plate at an estate auction after an 96-year old woman whose husband collected stuff in the 40's and 50's. It had old metal and wire hanging system which indeed dated it for at least several decades.
This piece is rather confusing. Large, about 16 inches across. Canton-type willow pattern, or precursor, but borders on front and back that are more typical of Japanese Arita ware! The writing is Chinese, however, and the mark on its back is Chengua ... BUT, is it real or later???
One expert I showed it to feels it's real, a precursor to later willow pattern ware. He liked the three small rusty colored flaws on the front... looks like could be from burst impurities? A Japanese dealer thought it was old Chinese. A Chinese dealer said it was 19th century Japanese!
I would welcome any thoughts you may have.
Your plate is indeed Japanese Arita and from about 1860. As a good confirmation there is several spur marks left in the glaze around the mark. This is very typical for Japanese porcelain. Spurs was never used in Chinese porcelain, I would say, after the Song dynasty, but then again that was before they made white porcelain with underglaze blue decoration, anyway.
The decoration is based on the 18th century Chinese export porcelain "willow pattern" decoration.
The mark is a Chenghua mark in a style commonly used during the Kangxi period on pieces copying pieces from the Chenghua period - so I can see why everybody have been quite confused..
I hope this clears this matter up :-)
The value should be slightly higher than an ordinary Arita plate of similar size, thanks to its interesting combination of different features