What should I do if A Yu (who won the first prize and was cheated) from Guiyang Ling Jun Store wants to return it?
The jadeite bought in the general activity lottery is non-refundable. Think of it as paying for classes, or seeing if people around you like it. Sold it to them. Generally, the quality of jadeite in that kind of activity is very poor, and good jadeite never needs to do activities. Buy A-grade jadeite, endless jewels.