Soul Gem (1/2): Roller Brawl
After opening the gate in Western Watch, make an immediate left. Along this detour is a bounce pad that takes you to a ledge where the Soul Gem rests.
Soul Gem (2/2): Star Strike
In Monkey Monk's Path, you'll pass a walkway with many spikes. Make a U-turn on the other side and hop across the raised stones to reach the Soul Gem you spotted earlier.
Iron Jaw Gulch
Soul Gem (1/3): Wind-Up
After crossing the first bridge into Iron Jaw Gulch proper, drop off the ledge to the right. There are some rooftops behind the cactus here that lead to a Soul Gem.
Soul Gem (2/3): Grim Creeper
After retrieving the second crank and crossing the bridge to Sun Smoked Strand, you'll approach a Swap Zone. Drop off the left ledge and follow the path to some bounce pads that will take you to a rooftop where the Soul Gem is hiding.
Soul Gem (3/3): Grilla Drilla
When you enter Okey-Dokey Corral, take out the Chompy Pod to reveal a bounce pad. Bounce to the roof and destroy the wooden water tower to obtain this.
Soul Gem (1/3): Boom Jet
Before grinding the mine cart rails after Baron Von Shellshock, hop to the ledge to the north. Use to scale crates to the left and reach a Soul Gem.
Soul Gem (2/3): Night Shift
After moving past the swinging crane hooks in Soggy Fields, hop across the goop via the tires. From here, you can jump from the wooden ledge onto a mesa, then onto an outcropping where you'll find another Soul Gem.
Soul Gem (3/3): Scorp
When crossing the Stack O' Trains, look to your right for a ledge you can reach. Hop to it to find this along the short path.