Granite stones for gardening are a long lasting and beautiful building material. Most granite stones are perfect for gardening decorations and will last for decades if not centuries.
Certain granite-like stones, however, may lose their color with prolonged exposition to the sun's UV light. Especially some blue natural stones may have this problem, for example the blue sodalite Azul Bahia.
Some natural granites may contain iron ore and are therefore prone to rust if continuously exposed to water. The oxidizing iron will change the color of those natural stones and can cause ugly big and ugly spots. Especially some red granites may have this problem.