About production date
When browsing or searching through ceramics or list of ceramics you may find in some cases a production date, rather than a production period such as ’’Meiji’’ or "Taisho".
How is it working and where is the date coming from?
When just a date is indicated here, it means that it is the exact date of manufacturing of the concerned piece. It means also that I have some evidence, generally because it is written on the piece itself or on the box.
If there is a question mark after the date, it means that I assume that the date is correct, but I have no evidence.
1878 - 1889
In a case of a range, it means that I am confident that the manufacturing took place at this period.