Despite not having yet met the tots in person, Nick and wife Nina have been introduced via Skype, and Nick spoke to United Kingdom television programme Good Morning Britain about his new grandchildren on Thursday.
"Both George and Amal are doing wonderfully well", he added, quipping, "George, well, his eyes were glazed so I'm not sure that he was sober!"
George Clooney's dad has revealed that the movie star is a hands-on father who is happy to take on nappy duty.
Nick, who previously opened up about the couple's bundles of joy, couldn't help put rave about his "beautiful" grandbabies once again. I'm supposed to be a reporter, therefore observant, but I really don't know how to describe one attractive baby from another handsome baby - these are two lovely babies. "The babies are handsome and are doing well".
Rande Gerber celebrated the arrival of George Clooneys twins with a "special delivery". "Of course, for her, that's a very small house".
"They are gorgeous. Nina swears they have George's nose", Nick said (via Us Weekly).
"My wife says I can't name them Casa and Amigos", George laughed to ET's Kevin Frazier at Las Vegas' CinemaCon earlier this year.
"Ella, Alexander and Amal are all healthy, happy and doing fine", the actor's publicist Stan Rosenfield confirmed in a statement to BBC News. But as Nick concluded in his video message to Good Morning Britain, the couple is "very grateful" for all the well-wishes and support they have received from their fans over the past few days.
These are the first children for both Amal and George.