Celtic Cross

This is what I've been working on for a co-worker. He wanted me to draw a Celtic Cross that looked old and made out of stone, and covered in vines. It took a while, but I did it. It's on a big piece of canvas board because the only way I could get all the details in it. He likes it, but he wanted me to color in the vines. This is the finished product, unless he asks me to color in anything else. He also decided that instead of a tatoo on his arm, it will be on his back and full size. Hope you have a high tolerance for pain. Opinions are welcomed.