Ben Affleck’s timely gift to galpal Jennifer Lopez has her heart ticking at high speed.

The handsome actor surprised the Latin lovely with a stunning $25,000 diamond Rolex watch. And if that wasn’t enough, her big-hearted beau dropped another $25,000 on a matching Rolex for J.Lo’s thrilled mom Guadalupe.

The couple, filming the movie “Jersey Girl” in Philadelphia, recently took a weekend break and scooted off to Atlantic City, N.J., for some fun.

“Jennifer and Ben walked into Bernie Robbins Jewelers, located in the Trump Marina Hotel Casino,” revealed an insider.

“Jennifer had on stunning 5-carat diamond earrings and was also wearing a diamond bracelet Ben had given her. The entire time they were in the store, Ben and Jennifer were either hugging or holding hands.

“Ben started looking at the Rolex watches and picked out a beautiful platinum watch with a diamond dial and bevel — and diamonds on the band.

“You could tell Jennifer loved the watch but she told Ben, ‘Honey, thank you, but I don’t want it. It’s beautiful but I just couldn’t.’

“But after she tried it on, Ben easily persuaded Jennifer he just had to get it for his girl.

“Then Ben did the most romantic thing he could. He stunned Jennifer by picking out an almost identical Rolex for her mother!

“Jennifer was floored. She was so happy she gave Ben a big hug and a kiss, and thanked him over and over.”

Ben, whose skin-tight jeans couldn’t possibly hold a wallet, pulled out a single credit card. The $50,000 purchase sailed through as if it were a $20 buy.

“It was definitely a classic Hollywood moment,” laughed the insider.