Later announced by that the GS Ball stood for Gold/Silver ball and was suppose to contain Celebi and was to follow Ash Ketchum around in the Gold/Silver series, however they decided at the last minute to save Celebi for the Pokémon movie "Pokémon Forever", thats why they got rid of the GS Ball and gave it to Kurt to never be seen in the series since.
So far the GS Ball's history is unknown however it is said to come from the Orange Island where Professor Ivy found it. It is however similar to the inscriptions in the ruins of Pokelantis and Pokemopolis, Ho-Oh and Lugia also seem to be related to the GS Ball mystery sense the GS seems to be standing for Gold which represents Ho-Oh, and S for Silver for Lugia. Lugia was also in the Orange Islands at the time of the GS Ball.
Sometime when Ash started his journey Professor Ivy discovered a mysterious Poké Ball and started to study it, she named it the GS ball since it had G and S looking symbols on the golden part. They were also unable to break it using heavy equipment, and found out little more than that it was indestructible.
The GS ball is a normal sized Poké Ball that doesn't seem to shrink like normal Poké Balls. Like most Poké Balls it is split horizontally down the middle into two different colors; Gold and Silver, with G and S shaped symbols on the upper golden part. It also has the black middle line separating the upper and lower parts with the button in the middle.