What materials have been used to make mosaics throughout history?

Well, older mosaics often were made of pieces of glass or small rough pieces of stone. Floor mosaics were made out of stone. A glue like paste was used to stick the pieces onto the walls. Michaelangelo's mosaics were often made out of colored tile and naturally colored stones. He also used glass.

Isee it as a little of both. they are showing off their clothes and designers to get you to buy it but also to be amazed by the designs and the style. 

Yes because in graphic design you add elements of art into one piece and/or program. although, you place together graphic designs on a computer,  you still have to know about the principles of design which is included in art.