Rai 3 was launched in December 1979 as Rete 3.
Rete 3 became Rai 3 in 1983. It launched a new logo corresponding with Rai's rebranding in the same year, which uses green as its color. In the bumpers, the logo was accompanied with a green three-sided pyramid.
In this logo, the Rai Tre typeface was modified (as with the Rai corporate logo at that time) and the pyramid officially became part of the logo.
This logo of RaiTre, which drops the pyramid, uses Rai's newly launched butterfly symbol, and maintains its now-standard green color, was introduced in 2000 according to the new graphic of Rai; like Rai Uno and Rai Due, during TV shows it was all white from 2000 to September 21, 2003 and with a green halo around from the same date to 2010.
This logo is used from May 2010, when Rai Tre changed name to Rai 3 (but is still called Rai Tre in a way since tre is Italian for three/3), and it's based on two squares. When the logos launched in 18th May, it didn't debut the new bumpers until 22nd November 2010. All of the new bumpers appeared on November 2010, and they're all in 16:9.
On September 12, 2016, Rai 3, along with Rai 1, Rai 2, and Rai 4, redesigned its logo and launched a new graphics package. The new design of Rai 3's logo maintains Rai's corporate logo, drops the second square at the right and gives an entirely new look for the number 3. The channel's iconic green color was maintained, albeit in a different shade.