Crassula perforata have the tiniest of blooms. They don’t really look like much. They crowd together at the tips of a growing stem which will then benefit when you cut the spent blooms off. It’s hard to tell without a magnifier when they’re spent or still in bloom. I would guess the tiny flowers are only 2mm across, but then I don’t know the metric system at all so I could be wrong. Here’s a life-size metric ruler, so they say, that shows what 2mm is.

The macro photo is not so clear. But it’s the best I’ve been able to get. It almost looks like a watercolor. Here is the same photo with a watercolor filter applied.