Both in Smythe and In CGCG the pronunciation of this diphthong is indicated as equivalent to the French ui as in huit. This is probably not correct because in French, u is a semi-vowel here, and i is a full-scale vowel ( it is like ueet), whereas, in Greek, all diphthongs are descending, that is their second component is something like a semivowel ( so it is like ujt).