Natural stone comes in a very wide variety of different colors, styles, and veining patterns. Most pure calcium based stones like marble and limestone are white when they contain no other minerals to give them color. Because the minerals that produce color show up randomly within a stone quarry, no two pieces are ever exactly the same. Some stones may have slight to moderate amounts of variation between them, meaning that there may be some pieces that are a little lighter or darker than the rest. Other stones, however, can have extreme amounts of variation. Some pieces may have colors that don’t match up with the surrounding tiles. Others may be dramatically lighter or darker than the others. When a lot of stone has produced a very varied color pattern, the stones need to be blended (random most of the time) by a professional during installation to get the most pleasing effect.