I bought my gecko a week ago and i can see that her colors arnt that nice as when i bought her. Could this be because i have to use a special lighting?
Most of the time the color fade or wash out is due to temperature. What temp is the surface reading at? I also noticed serious browning of one of my geckos back when I first started keeping and was using UV lighting.
It may be close to shedding. I don't use any lighting at all and there is plenty of color around here. I agree with Heather in saying that you should double check your temperatures. Are you using a suitable calcium/vitamin suppliment?
If you have a picture it would be much easier for us to tell you if it's shed related or not either...could be just her time to shed! I have a normal that gets a little dirty looking the week before she sheds.
She definitely looks like she's going into shed. I've noticed that Tang. Enigmas tend to change shades more often than most other morphs so you'll probably notice quite a bit of variation from month to month.