Of course.  Why are we here again?  
And Oan rings can create kryptonite.
		
		
	
	
from Wikie
Power rings of various wielders have exhibited (but are not limited to) the following:
    * Plasma based constructs limited to the willpower of the bearer
    * Semisentient computers, including Book of Oa reference, from laws to the history of the universe
    * Flight
    * Finite power source, but no longer limited to 24 hours. Kyle Rayner's ring was the first ring to absorb more power than originally thought, having stored the main power battery's energy following its explosion on Oa.
    * Force field generation
    * Radiation simulation, including Kryptonite
    * Upon death of the wielder, the ring automatically looks for a replacement.
Oh and Kyle did it during "Superman : King of the World"  Post Crisis.
:gl: :gl: :gl: