The X-Men: First Class actress explained that people almost never recognise her when she is out and about in normal clothing.
"I have this knack of being able to go out and not be recognised," Jones told Celebrity Gossip. "I wander around town in jeans and a T-shirt and my hair in a ponytail so no-one really spots me."
The actress, who is expecting her first child, said that even if people think they recognise her from somewhere they almost never believe it when she explains who she is.
"If I do get spotted, no-one believes it's me because they think I look far too small," Jones added. "I think the camera must add ten pounds!"
Jones recently revealed that she struggled to attain the body of her X-Men character Emma Frost because of the short amount of time she had to prepare before filming.
X-Men: First Class launches on June 1 in the UK and on June 3 in the US.
Watch the trailer for X-Men: First Class below: