Is Taihu Stone painted red?

No, Taihu stone is related to soil quality. The newly unearthed Taihu stone is red or orange. Over time, Taihu stone will turn gray-black. So the red color of Taihu stone is not sprayed. Taihu stone, also known as cave stone and rockery stone, is slowly formed after long-term erosion of limestone, including water stone and dry stone.