The Diphthongs of Irish

Modern Irish has five diphthongs, two original and three arising from loss of consonants (see below). The two original diphthongs are ua and ia. Their exact pronounciation depends on the quality of the following consonant, broad or slender. They both begin with a long vowel, ua with a long u and ia with a long i. The second part of the diphthong is the neutral vowel: before a broad consonant it's a schwa (like English but), and before a slender one it's a short e (like English bet).
 

uan	a lamb
uain	lambs
bua	victory
buaigh	win (a command)
iasc	fish
fial	generous
riail	a rule

The other three diphthongs arose from the loss of consonants, like English bough, light, right, etc. One is like the vowel in English right, beginning with a short a and moving to i:
 

adharc	a horn
deighilt	division
Tadhg	a personal name

Another is like English house, based again on an a but moving to u:
 

abha	a river
gabhar	a goat
cam	crooked

There is a third diphthong, similar to the second, but based on o instead of a. Nowadays it's only consistently distinguished in Donegal Irish; in southern dialects it has fallen in with the second one.