The artifacts look like a glowing white upside down pyramid. There will be a rainbow-like pulsation around it.
Like most of the achievements load up single player (Host \ Local -> Play Single Player) with Admin Cheats on. The admin console is at the top when you hit the START button on your controller.
Heres a list of all the exact commands you need to type in to teleport to each artifact. You will need to use the 'setplayerpos' command along with the x, y and z coordinate of where you want to go.
Clever: setplayerpos -32600 -83500 -6600
Skylord: setplayerpos -252700 -243100 -11500
Hunter: setplayerpos 54300 264600 -23700
Devourer: setplayerpos 275600 -271100 -25100
Pack: setplayerpos 87100 174900 -26200
Massive: setplayerpos 288000 136700 -24500
Immune: setplayerpos -101400 101700 -4300 (cave entrance)
Strong: setplayerpos -144500 -165000 200 (cave entrance)
For 'cave entrance' you will be teleported outside of the cave. If you spawn in the center, you misspelt or mistyped something as the center (0,0) is the default location.
Note: My achievement unlocked once I had collected them all and some were in storage at the time.
