The stone should be smooth and not angular, because from the perspective of Feng Shui, things with edges and corners have certain evil spirits, which will be bad for the owner over time. From a modern scientific perspective, smooth stones can make people feel comfortable.
Secondly, the more stones, the better. Don’t put too many stones. If there are too many stones, the yin energy will be strong and money will be easily damaged. On the other hand, stones are objects with a certain amount of radiation, and placing too many of them is bad for your health