Some crystals are not to be cleaned in sunlight, as the sunlight damages the crystal. For example, rose quartz is incompatible. The moonlight is a better option for others, or engulfing in the aforementioned white-golden energy. I read somewhere that crystals below around 4 on the Mohs scale are water soluble.
https://en.wikipedia.org/wiki/Mohs_scale Oftentimes, raw crystals are a collection of minerals and crystals, with varying hardness, and while one particular crystal might be hard enough, the others not, so it is advisable to practice caution when cleaning with water.