To get 100% on Crash Bandicoot Warped you need to finish all levels, collect all Gems and collect all Relics.
Every level has at least 1 White Gem to unlock (Other than Boss Levels). There are more ways to aquire White Gems than in the first Crash Bandiccot game. There are the usual 'destroy all boxes' Gems on every level plus some bonus Gems for clearing Death Routes and Coloured Gem paths. Coloured Gems require extra challenges.