As long as the plant's stem is still turgid, you needn't worry much. Jades (Crassula ovata) shut down in hot weather - the worst thing during the heat is to give them lots to drink. Cut back on the water, get them in a cooler place/more shade if possible, and let the plant be with minimal water (1x a week to ten days) until the cooler weather.

Thanks for the response. It's much cooler now, but new leaves are still taking on this coloring and falling off- still a few each day. And some get the hole you see in the smaller leaf. The inside looks like it's crystallizing. It's really strange.

What's the stem's status?

Under stressed conditions and when it's hot, there's a propensity to shed leaves, but you might have something entirely different.

Hmm- the stem seems ok, but then again, I'm not sure what to look for.

If it's still healthy (not softening / changing colour to mushy black). The plant could shed all of its leaves and still be fine, although that behavior isn't advised.