Hal Jordan Wearing A Blue Ring
Saint Walker creates a Blue Lantern ring on his own and gives it to the Red Lantern Hal Jordan, thereby curing him of the Red Lantern infection. Later in the series we’ll see another way to rid a person of a Red Lantern ring when Green Lantern Guy Gardner is healed by the living planet Mogo.
I could be wrong here but I think this might be the first time a person wore two different rings at the same time.
From – Green Lantern Vol. 4 #38