Jennifer Lopez's Lime Green Button-Up Dress Had a Pear-Shaped Stomach Cutout

Jennifer Lopez is hopping on the only-buttoned-once cardigan train, but in typical J.Lo fashion, she's doing it her own way.

On Monday, the multi-hyphenate took to Instagram to tease an upcoming project for JLo Beauty and Sephora. And in the process, she debuted a brand new trend.

In the series of photos, the "Let's Get Loud" singer showed off her glowing skin and caramel locks, as she looked away from the camera. The second photo shows J.Lo's profile as she looks down, and the third photo captured Lopez taking a selfie with her phone.

In the photos, she's wearing a long-sleeved, lime greenish-yellow ribbed button-up dress, with only two buttons fastened. The stomach portion of the collared tea-length dress was left totally unbuttoned, creating an ab-baring, pear-shaped cutout.

"My favorite color is neon anything 💛 💚 ," wrote Lopez. She continued to write that a "fun lil thing" for Sephora and JLo Beauty was "coming soon."

Speaking of something being in the works and coming soon, Lopez's boyfriend Ben Affleck was spotted looking at jewelry at a Los Angeles Tiffany & Co. with his mother Chris Anne Boldt and his one son, Samuel, 9. In photos obtained by Page Six, Affleck is seen browsing at the Westfield Century City store, and some of the jewelry cases that Affleck perused contained rings.

Given that the rekindled flames have been mansion hunting together, yachting around Europe, and introducing their kids, a ring seems like a very natural next step. And a source recently revealed to People that things between the two are getting serious.

"Since Jennifer and Ben are in it for the long run, it's just a natural step that they all spend time together with the kids," the source said.