Knock-offs of celebrity baubles are popular. Legions of women are walking around with a copy of Princess Diana's engagement ring on their fingers. Brad Pitt may not want that for his very own princess. If not, can he prevent knock-offs from taking place?
Maybe, if Pitt gets copyright protection on the ring's design. Such protection goes to creativity of ring design, but it takes very little to prove that under copyright law. That's unless there's something similar already out there in the marketplace. Then that designer might have a case against Pitt if their design predates his.
The good news is that Brad already owns the ring design copyright at this moment. Protection began with the ring's design completion. However, the actor has to formally register the copyright if he wants to keep the rights.
Someone could manufacture a copy with slight variation and possibly get around the design copyright. Much of that, however, is open to the law's interpretation. In other words, a judge might have the last say one way or the other.
Pitt could spend a small fortune taking everyone to court who might decide to copy the ring. There's one of him but legions of jewelers who might be willing to take their chances.
Of course, the jeweler who created the ring claims it took him a year to get the diamond cuts perfect so they'd fit together as they do. Other jewelers may not want to mess with the time and money it would take to make an exact copy anyway. Additionally, it would drive up the cost of the finished product, which isn't ideal.
Brad Pitt probably shouldn't worry about copycats. While knock-offs of his ring to Angelina Jolie may happen, chances are exact duplicates won't happen. He has better things to worry about, including planning a perfect wedding.