This is sometimes marked by placing a dieresis sign over the vowel which would otherwise be the weak one in the diphthong: "rido", "celo". 3.
Since newspapers know the vowel should have a dieresis on it they often misspell it as.
Regarding these poetic licenses one must consider three kinds of phenomena: (1) syneresis, (2) dieresis and (3) hiatus 1.