I have a white topaz ring that I've had for years. The topaz gets dirty easily with skin oils, etc. and that blocks the sparkle. I have to clean it after each time that I wear it. Otherwise it looks cloudy, dull and dirty. The sparkle does return after cleaning. Still, it's a hassle. Diamonds don't have that problem.
There may be something about the surface of white topaz that attracts dirt easily, as Pevi has found.