I agree the picture might not be very accurate, when it comes to jewels. And the lady on the left does not look like Queen Alexandra at all. The sash worn by the Prince of Wales (Edward VII) does not seem to correspond to any British order either.
Yet, the tiara worn by the lady on the right reminds me of a tiara worn by Empress Victoria of Germany ("Empress Frederick", formerly Victoria, Princess Royal in the UK, eldest daughter of Queen Victoria and Prince Albert, and wife of Frederick III, German Emperor and King of Prussia):