On a non-tiara note for just a second: Alia was quite an interesting figure. She was the first to really develop the role of queen consort in Jordan - the modern, working model that Queen Rania exemplifies today. She died tragically in a helicopter crash in 1977, leaving behind three children: Haya and Ali, and an adopted daughter named Abir. Hussein would marry once more after Alia's death, to Queen Noor.
Resuming gem discussion now: the tiara passed to her daughter, Princess Haya, who is now married to the Sheikh of Dubai. (You may recognize Haya from Ascot and other racing events, even if you're not a regular follower of these royal families.)
Princess Haya has loaned the tiara to Queen Rania rather frequently, particularly at the beginning of King Abdullah's reign when Rania didn't have a tiara collection of her own. (Genealogy check: Abdullah is the son of King Hussein and his second wife, Princess Muna. That makes him Haya's half brother.)
Rania shows off the versatility of the tiara with her varying hairstyles, but she also shows one of the downfalls: the halo effect.