Hi,

What are the techniques involved in painting stone similar to this?

The gray color variation seems like Perlin noise, possibly perturbed by an another noise generator to add a degree of spatial variation to the texture.

The cracks look like hand-drawn. It is also possible to generate such cracks procedurally by extending a random number of tapered lines (of slightly random length) from the center point, and perturbing the lines by noise that represents the statistical density of the material (for example).

The chiseled bumps (the ornaments) are usually hand-drawn as vectors, and converted to depth map. In modern modeling programs, it is possible to "bake" high-resolution geometry depth variations to texture a lower-density model in order to reduce geometry complexity considerably while preserving perceptible detail.

Normally you will start with the low poly base model.

You then import it into mudbox or zbrush where you will create a high poly model. This is where you will add the designs, the lines in the bricks, and the natural bumps in the stone.

The high poly model will then be baked into a bump map. The bump map will be applied to the low poly model to add in the graphical representation of the high poly model without the disadvantage of all those polys.

Finally, a texture map is added over the low poly model and bump map, creating the finished result.