It is very intresting , because I have heard that it was like an ultimatum to the Austria after the death of Rudolyf , because of the relations between two countries became worser.
They danced valses and chardashes.
It is said that the black dresses , gloves and black fans made a good combination with the diamonds and pearls.
K.R. wrote as follows: Ball at Anichkov was a strange one - with dames in black . On the black diamonds shined stronger. I did not understand , was it boaring or fun"
But your exlanation sound very reasonable.