We have learned all the letters of the Greek alphabet, and we have seen a few of the diphthongs. Here are all the diphthongs.

diphthong pronunciation example word
αι aisle χαίρειν
ει eight εἰμί
οι oil ἡ Φοίβη
αυ sauerkraut αὐτός
ου soup μου
υι suite υἱός (which means, "son, descendant")

There are two more, but they are quite unusual and we do not need to learn them now. (For the curious: they are ευ and ηυ, which are pronounced as the eu in feud.)