The late first lady of Israel, Nechama Rivlin. Her husband Reuven had been president since 2014. Sadly Nechama had pulmonary fibrosis (why the oxygen) and underwent a lung transplant March of last year. She died in June of complications from the transplant.
I shrug my shoulders: Queen Sofia has not been seen in some jewels for thirty years or more and there were demos in Madrid not that long ago and we just do not see the ice. Queen Letizia does not wear the ice much either.
I suspect it is just the result of an evolution of Letizia's own personal style, to simple and sleek, with few embellishments unless when the job requires her to. Plenty of examples for state visits hosted in Madrid, and on overseas trips to London and Tokyo.