The 'Firework' hitmaker will feature in the company's spring-summer advertising campaign for their forthcoming Pop Now collection, which is influenced by elements including pop art, music, disco and neon.
The 26-year-old singer has previously spoken of her love for quirky jewellery but one of her most treasured pieces was given to her by husband Russell Brand on their first date.
"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," she said.