The news comes two days after Jolie debuted a new prize on her ring finger during a trip to the Los Angeles County Museum of Art's Chinese Galleries with Pitt and their adopted son Pax on Wednesday (11Apr12) - and hours after a representative for jewellery designer Robert Procop, who created the Style of Jolie collection with the Oscar winner, confirmed he collaborated with the actor on the engagement ring.
A statement from Procop's rep reads: "Working closely with Brad Pitt to realise the star's vision for the ring, Robert Procop was able to source a diamond of the finest quality which was then transformed using Pitt's unique designs, cut with distinctive faceting to a shape and size that perfectly suits Angelina's long, slender fingers.
"Throughout, Brad Pitt remained heavily involved, overseeing every aspect of the creative design process from the perfect cut of the diamond centerpiece - an elongated tablet shape - to the finishing touches such as the mounting of a galaxy of smaller stones which are graduated in size and faceted to match, adding a crowning lustre to the ring.
"The full creative journey - from conception to completion - took a year, with Brad Pitt waiting until the perfect moment to unveil this special jewel to Angelina Jolie."
And now Pitt's manager Cynthia Pett-Dante has confirmed the news, stating, "It is a promise for the future and their kids are very happy."
She adds, "There's no date set at this time."
Pett-Dante also confirmed Pitt designed the ring.