The vowels ι and υ can be joined to the other vowels to make one syllable. These diphthongs are:
|αι||as in “aisle”|
|αυ||as in “hour”|
|ει||as in “eight”|
|ευ||the vowels of “met you”|
|ηυ||the vowels of “hey you”|
|οι||as in “oil”|
|ου||as in “group"|
When ι is added to η, ω, or a long α, it is not pronounced. Unless the first vowel is capitalized, the ι is written beneath it (ᾳ, ῃ, ῳ) and is called “iota subscript.” Pretend it isn’t there when you say the word.
Accents and breathings are placed over the second vowel of a diphthong, except for iota subscript or equivalent.
A diaeresis (two little dots, αϊ) indicates that two vowels are to be pronounced separately, not as a diphthong.
(note the breathing over the υ, the second letter of the diphthong. This is thus a two-syllable word even though it has three vowels.)
|Θρᾴκη||Thrace||(ignore the iota subscript in pronunciation)|
(a tricky one; since the accent and breathing are in front of the Α, Αι is not a diphthong in this word, and thus the ι is not pronounced. If the word were not capitalized, the iota would be a subscript: ᾇδης)