The 30-year-old actress shared a photo on Instagram of herself wearing a gold band on her left ring finger.
“This vintagey looking sparkly number from @foxandbond has me smiling today,” Duff captioned the shot, which shows her smiling with her left hand covering her mouth.
While Duff’s post may not be hinting at a potential engagement, her sister Haylie initially thought otherwise. “Ummm I thought this was something else,” Haylie, 33, commented.
A representative for Duff refused to comment on the ring when contacted by PEOPLE.
While this might not be the ring, an engagement may be on the horizon for Duff who is expecting her first child with boyfriend Matthew Koma.
In June, the Younger star announced her pregnancy writing, “Guess what guys! @matthewkoma and I made a little princess of our own and we couldn’t be more excited!!!!! 🤰🏼👶🏼🎀”
In the shot, Duff showed off her growing baby bump as Koma, 31, sweetly kissed her on the cheek.
Since her announcement, the actress has been very open about how difficult things are the second time around.
In July, Duff posted a photo of her bare baby bump and gave her Instagram followers an update on how she’s feeling.
“The boobs are big the belly is big the body is big. Man.. pregnancy is hard,” Duff captioned the mirror selfie of herself in a bikini.
“Giving love to all mamas who make it look effortless… this journey is hard as hell and also incredibly special. Lovely to have a little life inside and to day dream of all the new adventures to come buuuut almost impossible to get my own shoes on… sick of getting up 9 times a night to pee and looking at this weird body in the mirror that is not my own at the moment,” Duff added.