When I first saw crystal skulls, I was unsettled by them but they have grown on me so much over the past few months that I decided to buy half a dozen for the shop. 
Lapis Lazuli I  has natural colouring of royal blue and grey. It does not contain pyrite inclusions. It has interesting scars on the crown, on the face, on the temples and jawline. It is an earthy stone with a masculine energy and plenty of personality. 
Lapis Lazuli II has a bold appearance with a strong royal blue base and grey stripes with pyrite (golden dust) inclusions on the crown, in the eyes, and in a band along the mid section of the head covering the front, back and sides. There is also a good amount of pyrite on the base. Definitely an Egyptian feel to this one. 
Moss Agate I has quartz covering about two thirds of the skull on the one side particularly on the dome at the back and on the crown as well as the one side. The other side on the face has impressive deep green and highly defined moss inclusions forming a fascinating pattern with the banded agate from the face to the dome at the rear. This one is straight out of the forests of Siberia.   
Moss Agate II is deep green mossy inclusions throughout the clear agate with quartz inclusions densifying on the dome at the rear, the crown and the base. This one is very vibrant and interesting to look at. 
Moss Agate III is a lighter stone with a grey appearance and a little bit of druzy quartz on the one side near the base at the rear, on the rear dome and on the crown. The quartz also glitters in places. The moss inclusions are streaked through, giving this the appearance of a thing from under the ground. A fascinating skull with a lot of personality. 
Moss Agate IV is a smooth and shiny looking stone with plenty of moss which looks like it is suspended in liquid in the stone. The quartz inclusions and the banded agate form fascinating patterns against a mossy background in this stone. Heavily patterned on one side, on the face and on the crown of the head. A beautiful skull which would make a fine altar piece.