Why is my front tooth crown kind of gray at indoors and under shaded lighting.

different light sources will affect how teeth appear. This makes treating a single front tooth very challenging. 

It is a bit of a frustration in some cases that a tooth shade can look differently under different lighting situations.  Most dentists have full spectrum lighting in their office in an attempt to create the most universal situation but a crown can still look differently under varied lighting.  Unfortunately the only way to change the color of your tooth is to redo it.  And then there is no guarantee that it will not look varied next time.  A difficult situation.  Have a talk with your dentist and see if they have any suggestions.  Good luck!