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The tiara seems based on Queen Alexandra of the UK's now lost Rundell tiara.
Previously the Princess has only worn quite modest tiaras from the family's collection. I wonder if her wearing this tiara signifies a greater status for her (and of course her husband). She gave birth to a son earlier this year, who is destined to become Sultan one day unless her brother-in-law has a legitimate son.
At the same time he continues to be embroiled in drama after his short marriage to a Russian glamour model which resulted in a son being born a few years ago that resulted in him abdicating as King of Malaysia. From what I have read he is now involved in legal proceedings about the child with the baby's mother in the UK about funding for the child.