Here is the full list of all 8 Pilfer achievements.
Acquire a loot with a total worth of 100 coins.
Acquire a loot with a total worth of 500 coins.
Acquire a loot with a total worth of 2000 coins.
Acquire a loot with a total worth of 5000 coins.
Find all the rings and store them in your hideout.
Find all the swords and store them in your hideout.
Find all the gems and store them in your hideout.
Successfully pick a lock.