Page "Survivor (TV series)" Paragraph 34

In Guatemala, the hidden immunity idol was not returned to the game after its use.

Since then, if the idol is played, or the player with the idol leaves the game without playing it, the idol is replaced at a new location to be found, as long as the means by which clues to the idol's location are still given out and that the idol can still be played at following Tribal Councils.

In Gabon, the contestants unanimously decided to throw a hidden immunity idol into the sea.

In this case it was not replaced at a new location.

In some seasons, false hidden immunity idols have been fashioned by contestants ; these have no value at Tribal Council.

If a contestant plays a false hidden immunity idol, the host would toss it into the fire pit.

Probst has stated that the production team indirectly encourage contestants to create these fakes by means of supplying the camp with many materials that could be used to fashion the idol.