Palpatine's lightsaber was a Sith blade created by the Dark Lord of the Sith, Darth Sidous. A patron of the arts,Palpatine's weapon was of an elegant and graceful design, with a refined electrum finish. However, Palpatine was of the opinion that the Sith had outgrown the use of lightsabers, and wielded it merely as an affectation to mock the Jedi. Indeed, Palpatine wielded it his handcrafted weapon with sufficient skill to overcome three of the Jedi Order's finest duelists, and battle Swordmaster Mace Windu to a standstill. However, Palpatine would lose to Windu, inadvertently dropping his lightsaber out of his office window during the engagement, where it would be lost in the alleyways and gutters of the Coruscant.

Source: Starwars.wikia.com