Board Thread:Questions and Answers/@comment-203.81.212.210-20150124161407/@comment-25889587-20150124162100

Upgrade the one with the lowest chance. Put priority to the one that increases the highest per upgrade. Crystal Pear Earring is an A-grade treasure, so upgrading it to +9 wouldn't be a pain.

4 Layer Cake is an attractive one to upgrade. I suggest you upgrade that one and Crystal Pearl Earring first.