The finished product, 70X50 cm of hard work with a tiny brush. (click on it to enlarge)
Other stones are hopelessly irregular - but most of the time rectangular-ish. And because the light comes from above, the shadow will usually be under the stone.
Above the most varied piece of stone wall. Irregular, in size, colour, material, shadow and shade... I must admit that I "simplified" it a bit. I do that often, also with tiled roofs. (The brain still accepts it as a roof - although the tiles are much bigger than in real life...)