Power Gem

Power Gems are only seen in Crash Tag Team Racing.

They are purple gem stones that activate the gateways to each of Von Clutch's Motor World's lands. You have to unlock the jump pads in each land with Power Crystals to unlock the next land.

Purple Gems
Power Gems closely resemble Purple gems from various other Crash games and like all gem types, unlock a new path (in this case, the path to the next land).