Quartz and Artifical Marble tops are a mixture of natural and man-made materials. There will be variances in veining, colour and grain pattern between the top you get and the small sample in the store of the pictures in this catalogue.
Hard water spots are caused by minerals in the water. Some municipalities have very hard water and this has been known to cause spotting. Drying the tops after using them will go along way in avoiding water spots in the future.