Russell Brand is a diamond fella

The British funnyman - who married the singer in October after a year-long romance - was instantly smitten with the brunette beauty and nicknamed her his "mermaid" because of the way she made him feel.

When quizzed about her long necklace by Britain's Grazia magazine, she said: "Russell gave this to me on our first date. It's a Hindu hand of peace. But they're not beads, they are black diamonds. He gave me black diamonds on our very first date."

Russell gave her the jewels as he drove her home from dinner and she asked if she could have a copy of his autobiography which was in the car.

She added: "I asked him if could have it. My hair was long and wavy at the time and he kept calling me a mermaid. He opened the book and wrote in it, 'You're a mermaid and I'm drowning.' Then he put this necklace on me."

Katy says Russell is now her "muse", and her relationship with the 35-year-old actor has inspired a lot of her new material.

The 'Firework' hitmaker - who released her third studio LP 'Teenage Dream' in August 2010 - said: "It's funny because a lot of tracks were written before, but it's as if I knew he was going to be in my life. He is definitely my muse, or rather his love is. On top of that he's very handsome and very, very funny.

"What can I say? He's brilliant. Every day he amazes me. He makes me laugh like no one else. We are each other's perfect match."