The actress was happy to show off her sizeable diamond, which she has recently revealed fiancé Justin Timberlake picked out all by himself.
"I had no say whatsoever [in the ring]. I don't micromanage," she told US publication InStyle.
The 30-year-old added: "He is fearless in his choices and has a real eye for design. And I'll be honest: he has better taste than I do. It's hilarious."
The Sexyback singer may have also helped with Jessica's outfit for the ESPY awards – he often helps pick out her red carpet looks.
Jessica complemented her thigh-skimming Christian Dior Resort 2013 dress with an eye-catching pair of Nicholas Kirkwood for Roksanda Ilincic Spring 2012 pumps with luminous yellow chunky heels.
She was clearly pleased with her footwear, writing on Twitter: "I know the #espys are about sports and stuff but LOOK AT MY SHOES!"
Jessica presented the Best Breakthrough Athlete trophy to NBA player Jeremy Lin, of the New York Knicks.
She was helped out by American Football player Tim Tebow, handsome quarterback with the New York jets.
Other famous ladies at the ceremony included Zoey Deschanel, Hayden Panettiere and Maria Sharapova, who took home the Best Tennis Player award.