Thank you, Erik, for this research and interesting find.
I do regret that Crown Princess Mary did not wear her ruby parure. I think it would have been very appropriate for such a royal-royal occasion. A cautious humility from Mary in order not to "outshine" Queen Margrethe and Queen Maxima? Well, Crown Princess Mary usually wears her ruby parure for New Year's banquets (or also for Queen Margrethe II's 40th reign anniversary in 2012), and nobody, then, has ever blamed her for supposedly "outshining" her royal mother-in-law. As for Queen Maxima... well, who could outshine her, with this whopper sapphire tiara and this gorgeous Inauguration dress??? Impossible... even with a full Napoleonic ruby parure!!!
(Source: The Dutch Royal House's Twitter account: https://twitter.com/koninklijkhuis/status/577941974440939521)