Brad Pitt pokes fun at Rihanna (and Jay Z) for her Diamond Ball Gala

At Rihanna’s Diamond Ball Gala on Thursday night, pal Brad Pitt did the honors of introducing the 26-year-old to the stage -- but not without injecting a little humor into the mix.

As a photo of a young Rihanna appeared on the screen to an audience filled with stars including Kim Kardashian, Kris Jenner, Big Sean, Adrienne Bailon, Salma Hayek, Fabolous and more, Pitt kicked things off by cheekily saying, “I’ve often asked the very questions you yourself are asking right now -- what ... went wrong?”

“Look at the young girl before you, all full of hopes and dreams, living a humble existence in Barbados, her whole life ahead of her,” Pitt continued, as E! News reported.

Somehow the fashion and beauty icon found herself with “a bad crowd led by the dubious and nefarious character known as the Jay Z,” Pitt added. “For those of you not in the know, the Jay Z was an evil impresario known for turning out hit records and ripping insane lyrics and fresh beats. Needless to say it was all downhill from there.”

He went on to note, tongue in cheek, that her titles included executive producer, fashion designer, actress, philanthropist and singer. Still, Pitt topped things off by telling her, “Just do something with your life.”

That’s when Rihanna, who had arrived on the red carpet in a pink satin Zac Posen off-the-shoulder gown accessorized with a diamond Chopard necklace, appeared in a navy blue structured Zac Posen gown. She took the stage to blend her biggest hits, including “Shine Bright Like a Diamond,” “Umbrella” and “Stay.” At one point during the performance, she conducted the orchestra. Note to Pitt: Add that to your list of the multihyphenate’s accomplishments.

Rihanna’s fashion choices were very much appropriate for the Beverly Hills black-tie fundraiser in support of her charity, the Clara Lionel Foundation. Created to honor her grandparents Clara and Lionel Brathwaite, the foundation’s goal is to improve the quality of life for communities globally in the areas of health, education, arts and culture.

But the fashion choices of Kim Kardashian and momager Kris Jenner -- that was another story. The mother-daughter pair served up head-scratching, er, unique looks. Both ladies donned dark, hello-cleavage numbers. Kardashian, 34, opted for a fishnet Balenciaga dress, while Jenner, 60, wore a Dolce & Gabbana suit embellished with a lace top.

The reality-TV divas made time to mingle with Rihanna and singer Big Sean, who also hit the dais to perform his recent hits “Clique” and “I Don’t ... With You.”

In addition to the performances at the gala, attendees had a chance to bid on items including a Kanye West Experience Tour package, a Gucci package and a Damien Hirst piece of jewelry that went to Salma Hayek for $190,000.

In the end, however, the night revolved around Rihanna, who previously told Rolling Stone (via UsWeekly): “There is truly nothing I’m more proud of, and we’ve just gotten started.”

Kardashian wore what? Pitt said what? Follow me on Twitter: @ChristyKhoshaba