You may have noticed that most diphthongs look alike to the two-vowels vowels and combinations ευ and αυ. However, they are distinguished by the fact that over ι and υ there are special signs, similar to the Umlaut of German language. These signs are called diaeresis and are always used to separate a vowels' digraph, having as a result the independent pronunciation of each vowel the digraph is consisted of.