Crystal Dragon

I am including the crystal dragon in the list of species simply because there is one living in a human city.  See Brightscales 
Crystal Dragons are made of crystal - but it is a fluid crystal that moves very nicely and without sound. Obviously this movement and the fluidity of the crystal is magical. The Dragon can change the shade of its color from pale to dark and in between.
This most verisitile of all is the pure crustal dragon as it is made of a diamond like crystal. As it is clear it can become invisible! It can also change the hue of its crystal to give itself some color - normally not to the extent that colored crystal dragons can - but enough to read its emotions and actually see it. So it can turn pale colors.