Though I don't know about Chinese, I think it can be either of the two. We don't usually use 寳 in Japan nowadays, but some people intentionally still use it because they want to add the classic mood/flavor. If it's Japanese, 寳洲 would be the name of the artist / craft man. 作 usually means "made by". I won't be surprise if the artist used the old character 寳 for his name. Some artists love orotund / pretentious things.