It looks like Angelina Jolie and Brad Pitt may at last be ready to take the plunge. On April 11, Jolie was spotted at an L.A. museum wearing what appears to be an engagement ring. Jeweler Robert Procop, who worked with the actress on her Style of Jolie line, confirms that he collaborated with Pitt on the design. "He wanted every aspect of it to be perfect," Procop says of the sparkler, which features side diamonds specially cut to encircle Jolie's finger. So is the couple finally giving in to pressure from their children to get married? You bet! "It is a promise for the future and their kids are very happy," Pitt's manager tells PEOPLE. "There's no date set at this time."