Cobblestone There are natural pebbles and machine-made pebbles. The natural pebbles are from the river bed. The colors mainly include gray, cyan and dark red. After cleaning, screening, sorting and other processes. And the mechanical grinding pebble surface is smooth and wear-resistant. At the same time, it can be made into various specifications of pebbles according to different requirements of users. It is widely used in pavement, Park rockery, bonsai filling materials and so on.