Hello,
there is a Thomas, Patrick and a William Dimond (Diamond) mentioned in a town map of 1848 - perhaps the one of these is John's father.
In Griffith's Valuation Land Survey from 1856, William, Patrick and John are mentioned.
There are a number of Dimond/Diamond families in the locality in the 1901 and 1911 census.
In St. Bridgid's graveyard, there is a headstone:
Pray for the soul of Joh Dimond who died December 24th 1923 and his daugher Anne Dimond died March 28th 1923
John J Dimond died October 8th 1960
His wife Mary died 28th February 1989
RIP
Erected by Mary Dimond and children
I remember Mary Diamond who died in 1989 very well. She was already a widow in my childhood and was a neighbour of ours.
Hope this is helpful.
regards
Dolores O'Shea
Portumna