Color. Saturation. Contrast. Unless those are granit stones, it needs those 3 aspects. Take a picture of something green for example. Grass or something. Use it as a Monitor-Layer (not sure how this is called in PS/English, im using GIMP/german version) at a low opacity (eg. 15-20% would do the job), merge both monitor and base layer and increase saturation, lower brightness a bit (-10%) and increase contrast (+5%).
Wfr, Sindwiller