The star count is shown at the beginning of the product page in the first paragraph as 3-star, 4-star, and 5-star. The number of stars indicates the number of attributes present in the rock. A lot of rocks have 3-stars. Four-star and five-star counts are progressively fewer. Five-star being the best.
Here's a list of attributes:
1. The entire rock is sculpted entirely to a human-like or animal-like profile.
2. The rock has one or more sculpted images and shapes.
3. Etched out petroglyphs on the surface of the rock. A petroglyph is where the rock has been carved.
4. Rocks having faces within faces attributes means that you may look at a section of the rock and see one image. Then redirect your attention back to same image to see that it's different. Paintings on rocks are referred to as pictographs.
5. Holes and depressed surfaces. Often, they would create a hole in the rock to represent a cave. Within the cave would be a silhouette of a person.
The featured image shown here shows examples of the types of rocks you'll be looking for.
would be a silhouette of a person.