Synthetic granite is a man-made material commonly referred to as Quartz. Nonetheless, you ask a great question because some stones are color-enhanced. The best way to tell is to look on the side edges and in the back of the slabs. If it is color-enhanced you will see only a thin coat and drips of the dark color while the color on the rest of the sides and the back of the slab are white or whitish even beige-ish. Find the same pattern and colors behind the slab as is in the front, although you will see a much lighter colored version of said pattern. Granite colours can come in black to white and everything in between. Interstone Marble and Granite has a superb variety of stones for you to peruse.