Going on with the 'colours of the grand duchesses' court gowns' theme, Meriel Buchanan in 'Memories of Imperial Russia' recounts the court procession at the Feast of the Epiphany in 1911 where she recalled the "blaze of exquisite jewels, the resplendent old court dresses with their stiffly-embroidered gold petticoats, their long hanging sleeves and trains of velvet......Much of the details I have forgotten [how could you, Meriel], but......I can recall....the vivid, cornflower blue of the Grand Duchess Cyrill- the marvellous sapphires and diamonds that flashed on her kakoshnik; the olive green of the ofer court ladies; the ruby velvet of the Demoiselles d'Honneur". She also mentions "the soft, rose-coloured velvet overdress of one of the young Grand Duchesses" but not which Grand Duchess it was! The Dowager Empress was wearing "cream-white velvet" and Alexandra wasn't mentioned - it isn't clear if she was there - the Emperor came to St Petersburg especially for the event so perhaps she stayed behind.
I wondered at first if the 'Xenia' court gown might actually be that of Victoria Melita, but cornflower blue is actually a light blue, a little like the forum borders in fact but even lighter. So I think we could add this colour to the list:
Ladies in waiting: green
Maids of honour: crimson
Special colours of the Grand Duchesses:
Xenia Alexandrovna: Dark blue
Maria Pavlovna the Elder: Dark orange
Ella: aqua
Elizabeth Mavrikievna: dull yellow
Victoria Melita: mid/light blue
I had a look in 'Greek Minny's' journals but she was rather lukewarm about the whole Russia thing and didn't go into detail, alas.