Symbols as mark are used on domestic wares since late Ming dynasty. During the Shunzhi, Kangxi and Yongzheng era, symbols and characters as mark became more and more popular on domestic porcelain. After Qianlong era reign marks gained its popularity and symbols as mark lost significance.
Most 18th century export porcelain are not marked besides double circle marks while Chinese domestic wares are often marked.
Before 1678 reign marks were not allowed to use on porcelain because of superstition. A
broken porcelain with current reign mark would bring bad luck to the new dynasty. After the Manchu conquest the political climate was turbulent. The new sovereign didn't want to provoke Chinese
people and allowed them to use reign marks of Ming dynasty which was a way to show their demonstrating attitude.