The Laguz Gem (化身の宝珠 Keshin no hōshu) is an item that appears exclusively in Fire Emblem: Radiant Dawn. The Laguz Gem transforms its Laguz user for the whole chapter when it is used.
The first Laguz Gem available in the game is held by Giffca, while the second is held by Nasir, if he survives along with Gareth.
A Laguz Gem can also be obtained in Chapter 4-3 on the same space that Numida is positioned on. The best way to acquire it is to shove Numida, have Sothe assume Numida's original position and thereafter have his Luck stat trigger the unearthing of the gem.