The ceilings are constructed of vaults of gold, and there are columns made of violet marble, and the marble is from Egypt. There are mosaics, and they are some of the most famous mosaics in the world.
Procopius further writes about these,“The whole ceiling is overlaid with pure gold, which adds glory to the beauty, yet the light reflected from the stones prevails, shining out in rivalry with the gold” (Procopius, pg. 25).
There is a complete mosaic program, and the tesserae, or small squares of glass which make up the mosaic, are sandwiched with gold leaf beneath them, then affixed to the structure over the gold leafing, and angled in just a way so that they capture light” (Nova Film).
Emperor Justinian donated gilded silver for the walls, so that everywhere you looked from within the church, you saw the sparkle of gold.