I’m in India, and we have quite a number of Israeli tourists and business travellers visiting here. From what I’ve seen, I’ve noticed practically every racial feature in most of them. I really wouldn’t be able to tell a Jew apart from anyone else, atleast not all the time.
For what it’s worth, Jews can usually pick each other out of a crowd (a.k.a. “Jewdar,” kind of like the phenomenon of “Gaydar”). There are certain indiscribably Jewish features that most Jews have in common. It’s not perfect — I’d say maybe 70% accuracy.