Gwyneth Paltrow is so close to ex-husband Chris Martin that she thinks of him as a "brother".

The 45-year-old actress shares two children with Coldplay frontman Chris, from whom she split in 2014, with the pair hitting headlines when they described their divorce as a "conscious uncoupling".

Since then, Gwyneth and Chris have remained on good terms, with the Iron Man star describing their "familial" relationship as she appeared on U.S. TV show The Late Show With Stephen Colbert on Thursday night (25Jan18).

As Stephen congratulated Gwyneth on her engagement to Brad Falchuk, he showed a picture of the betrothed pair at a brunch alongside Chris and commented on how close the former husband and wife still are.

"Very much so. He's like my brother. Very familial. It's nice. Great," Gwyneth said.

And when Stephen joked that it's strange to say someone you had children with is like a brother, Gwyneth hit back "which would explain the divorce", before adding: "Just kidding!"

Gwyneth and Chris' friendly relationship now doesn't mean they didn't struggle when going through the divorce process though.

Asked if their "conscious uncoupling" was a sign they were "more evolved" than other couples, Gwyneth replied: "Definitely not... divorce is terrible. It was very painful and really hard. We genuinely wanted our kids to be as unscathed as possible."

Stephen had earlier showed a picture of Gwyneth's stunning engagement ring from Glee creator Brad and asked the actress to detail the type of jewel.

"I believe it's a sapphire," Gwyneth said, before admitting she had no idea what kind of cut it is.