Yes, it is beautiful gown, but I think it was a little bit too intense color for THE DAY OF HER HUSBAND... Poor WA was a gray mouse next to her. IMO she ought to have chosen a more moderate color.
LOL, I'm not sure what colour could have been more moderate for the day you become a queen!
I think colour choices for such a unique event as the inauguration of your husband as King of the Netherlands would have been limited. Consideration would have had to have been made for things like the backdrop of the golden thrones, the choir screen and flooring of the church, the blue carpet used between the palace and the church, your husbands white, red and gold mantle, the sashes to be worn, not to mention symbolisms such as the colours of the Dutch flag and Orange or colours used in past inaugurations.
As such, I think in all honesty you would want to choose out of Red, white, blue, gold, possibly silver or yellow and the unlikely colour of orange! I think red would have been to clashing against ones hunsband's mantle. White I think should be reserved for brides or regnal queens. Gold would have been far too flashy. Silver might have been ok, but would limit you on fabrics if you wanted a silver rather than gray look. Yellow and orange would have made you stand out like a sore thumb if moderation is your thing.
So personally, I think the royal/sapphire blue colour was the best choice as it completed the symbolism of colours...not to mention it was the same colour worn by Queen Juliana for her inauguration!