Here is a simple guide on how to obtain the Jewelry Ang Pau.
A. Mutant Invasion Quest for Jewelry Ang Pau
Note: The monster’s that you are hunting in these quest lines may drop unique items that are useful for the Rampage quest so if you are planning to do the Rampage quest in the future, it is advised to keep those unique items for the rampage quest line here : [QUEST] A guide for the Rampage quest - #2
You may also obtain Jewelry Ang Pau through monster drop.
These group of monsters has a chance to drop Jewelry Ang Pau: