In Sindarin the diphthongs are written ae, oi, ei, oe, ui, and au. Other combinations are not diphthongal. The writing of final au as aw is in accordance with English custom, but is actually not uncommon in Fëanorian spellings.
All these diphthongs72 were falling diphthongs, that to stressed on the first element, and composed of the simple vowels run together. Thus ai, ei, oi, ui are intended to be pronounced respectively as the vowels in English rye (not ray), grey, boy, ruin: and au (aw) as in loud, how and not as in laud, haw.
There is nothing in English closely corresponding to ae, oe, eu;ae and oe may be pronounced as ai, oi.
STRESSThe position of the 'accent' or stress is not marked, since in the Eldarin languages concerned its place is determined by the form of the word. In words of two syllables it falls in practically all cases on the first syllable. In longer words it falls on the last syllable but one, where that contains a long vowel, a diphthong, or a vowel followed by two (or more) consonants. Where the last syllable but one contains (as often) a short vowel followed by only one (or no) consonant, the stress falls on the syllable before it, the third from the end. Words of the last form are favoured in the Eldarin languages, especially Quenya.
In the following examples the stressed vowel is marked by a capital letter: isIldur, Orome, erEssëa, fËanor, ancAlima, elentÁri; dEnethor, periAnnath, ecthElion, pelArgir, silIvren. Words of the type elentÁri 'star-queen' seldom occur in Quenya where the vowel is é, á, ó, unless (as in this case) they are compounds; they are commoner with the vowels í, ú, as andÚne 'sunset, west'. They do not occur in Sindarin except in compounds. Note that Sindarin dh, th, ch are single consonants and represent single letters in the original scripts.
NOTEIn names drawn from other languages than Eldarin the same values for the letters are intended, where not specially described above, except in the case of Dwarvish. In Dwarvish, which did not possess the sounds represented above by th and ch(kh), th and kh are aspirates, that is t or k followed by an h, more or less as in backhand, outhouse.
Where z occurs the sound intended is that of English z. gh in the Black Speech and Orkish represents a 'back spirant' (related to g as dh to d); as in ghâsh and agh.
The 'outer' or Mannish names of the Dwarves have been given Northern forms, but the letter-values are those described. So also in the case of the personal and place-names of Rohan (where they have not been modernized), except that here éa and éo are diphthongs, which may be represented by the ea of English bear, and the eo of Theobald; y is the modified u. The modernized forms are easily recognized and are intended to be pronounced as in English. They are mostly place-names: as Dunharrow (for Dúnharg), except Shadowfax and Wormtongue.