The Premier Ball (プレミアボール Premier Ball) was created for a special event. It is entirely white except for the band around the middle which is red. According to the official Pokémon Colosseum game guide, it has the same catch rate as a regular Poké Ball, but "it looks cooler."
It can be obtained by purchasing 10 regular Poké Balls from a shop (Generation III onward).
Because you obtain a free Premier Ball when purchasing a least 10 regular Poké Balls from a shop, it is more money-efficient to just buy 10 Poké Balls at a time, and repeating the process if purchasing more.