The couple -- dressed pretty casually -- was spotted in Tribeca, but reportedly made their way to a jeweler in Midtown Thursday, a few days after getting engaged.
Foster popped the question in Anacapri, Italy and Katharine confirmed the engagement by posting a text exchange where someone described her ring as "beautiful and classic." We also have a photo of her showing it off at dinner earlier this week.
She was wearing a ring on her ring finger Thursday afternoon, so it's possible she was getting it resized ... or maybe they were shopping for Foster.
The two began dating last year. It'll be Foster's fifth, and Katharine's second marriage.