Well it is raining.....

These all here are Dyckia fosteriana
but some differences may come up when the plant is wet.
Yes, these two below are just wet, damp wet.
But they are different: one is the rubra form and the other the green one is the plain Dyckia fosteriana.
This you will note just when the plants are wet. If it dryes it gets the fine lookings of the above plant.
Meanwhile.........

...if we keep a fosteriana under the heavy rain it may loose all its white/silver scales
and stay nude as these two up and down here.
It is a chance to see which is rubra but for this proposal just spray good water on it.
Yes, they recover some of the lost scales but most may be lost forever.
The scales come up from the plant skin as our skin cells do.
We form a layer of keratin all over our skin. This keratin layer is composed by death cells that once were deep within our skin.
Dyckias do something similar but they have a limited source of cells to be transformed into these protective scales. This has a reason. Nature does no waste. A leaf for as much as it lives it is not as long lived as an animal. A plant may loose leaves without dying and animals can not loose parts along the way....
So if you want your fosteriana and other well scaled Dyckia looking whitish do not hose it nor leave it under heavy rain.