Felicity Jones had to have her teeth capped while playing Ruth Bader Ginsburg.

The 35-year-old actress portrays Ruth, who was the second ever Associate Justice of the Supreme Court, in the 2018 legal drama 'On the Basis of Sex' and the Felicity admitted that to replicate the judge's ''perfectly formed American teeth'' she had to receive dental crowns - a tooth-shaped cap placed over a tooth to improve appearance - over her pointed teeth.

Speaking on 'The Graham Norton Show', the English actress said: ''I kept looking at Ruth and she had the most perfectly formed American teeth, and then I would look at mine, which are distinctly British and a little bit gnarly, so I had my pointy ones capped while I was shooting. It sounds painful but it wasn't too bad.''

The biographical legal drama follows a young Ruth as a struggling attorney and new mother who takes on a groundbreaking tax case with her husband, attorney Martin Ginsburg (Armie Hammer), which could change the direction of her career and sets her on a path to fight for gender equality in the US.

The 'Rouge One: A Star Wars Story' actress went on to praise Ruth and insisted she is ''so beloved'' the only person who can live up to the real person is Ruth herself but she did her best as the actress telling her life story on screen.

She said: ''She is so beloved that really the only person that could play Ruth Bader Ginsburg is Ruth Bader Ginsburg so I definitely had a lot to live up to.''

Armie, 32, added that his character Martin was ''too good to be true'' and such an ''amazing person'' that he didn't know ''what to do with him''.

He said: ''When I read the script it described a husband that was incredibly progressive and supportive and perfect and charming and I thought, 'This guy is too good to be true,' so I employed a researcher to find out where the bodies were buried!

''I felt sure there was something wrong with him, but he really was the most amazing person and everyone loved him. He was so perfect that, as an actor, I found it hard to know what to do with him.''

'The Graham Norton Show' airs on BBC One on Friday (15.02.19) 10.35pm.