The "Transformers: Age of Extinction" star got engaged to the photographer, 21, on 1 July (20), with the pair confirming the news 10 days later. Now, followers of the pair are convinced they've already tied the knot after Nicola shared the cryptic picture.
In the photo, posted on her Instagram Story, the couple is seen holding hands with the new jewellery clearly visible on Brooklyn's finger.
A social media user who runs a fan account for the eldest child of ex-soccer star David Beckham and Spice Girls star-turned-fashion mogul Victoria later shared the post on the page's feed, prompting people to comment that a wedding has already taken place.
"They are married... Brooklyn has the ring," wrote one person, while another heightened the speculation, adding, "She is pregnant."
The couple has yet to address the rumours.