This achievement unlocked after I completed 3 puzzles from Easy, Medium, to Hard. I didn't have to do an Expert puzzle for it to unlock.
You can use hints liberally, and you get one reshuffle per game. These make the puzzles pretty much a cakewalk even on Hard.
Comment by WcG iFredy2 (if you're having issues): I noticed that when I was playing through Puzzle Pack No.1 it just unlocked automatically when I did an Easy, Medium, Hard them another Hard level, but from memory I'm sure I had to do 4.