Queen Astrid received it for the birth of Boudewijn so it would be suiting if it went to Fabiola. However we've never seen it. Im afraid the piece was either dismantled or sold ages ago.
If it had been with Fabiola she would have left it in Belgium as it was a Royal piece. The only option would be if she left it to Gabriel for his future wife. But that would be a long shot as she knew Elisabeth would be the future monarch and was lacking a tiara as well. She might have tried to push Paola in leaving the Art Deco bandeau of Queen Elisabeth to the Duchess of Brabant. But all of that is pure speculation.