The Revelations of a Lady:
Her Gown
Her gown with its graceful drapes and folds comes from the traditional toga 'worn' by the statues of Classical Antiquity.
Her Torch
She raises a torch, symbol of enlightenment, with her right arm as did her ancient sisters from Classical Antiquity.
Her Crown
Her headdress has seen countless versions (a single star in her early modern depiction of 1872), from laurel wreath in 1924 to her first tiara in 1928 to bare head in her later versions (till the video game Bioshock Infinite, in the 21C, gave her a tiara once more to wear on a specific mural that gives one pause: are there alternate versions of the Columbia?).
Her Limbs
With thigh exposed, she was daring in 1924; entirely chaste in her 1928 version, then demure with the years that followed with just a peek showing, which was then fully covered once more in 1992.
Her Hues
Blue for royalty. White for purity. The Columbia is indeed a royal figure, standing tall as a fair column on a half-finished pyramid, and reaching to the Heavens with her torch blazing with divine light. She is the mirror image of another royal figure who stands upon heavenly clouds and looks down upon humanity with her divine light and grace.
Other Emblems
Just as with her ancient sisters, her emblems have varied throughout the centuries. In Gast's painting, her book is a symbol of knowledge and enlightenment, and the telegraph wire a symbol of modern technology and progress. In 1924, she carried a wheat sheaf and shield, respectively symbols of prosperity and power.