First select the "Learn To Play" option in the menu to play the tutorial. Progress to the right until you get past the part where it says "Press jump on walls to climb to higher places". You will now have the ability to climb walls. Instead of scaling that wall, go all the way LEFT where you started the level. Keep tapping
to scale that left most wall and eventually you will reach the top. Now run as far left as possible and you should see a blue gem there. Pick it up and you will get this achievement as well as progress toward the 4 gem related achievements (it seems there are 20 gems hidden throughout the game and you need to find each of them for those achievements).