You will find even better ones in the Enhancement Pack and other modern graphics mods.
Some of the original lamp glass textures are very blotchy due to the single palette limit that used to apply to the first Thief game. These were left like that for Thief 2.
You can replace them for your FM by right clicking on each of the images below and saving them to youre FM's "obj\txt16" folder:
You will find even better ones in the Enhancement Pack and other modern graphics mods.