Nielo or Niello: How To spell?
The word Nielo is misspelled against Niello, a noun meaning "A metallic alloy of a deep black color."
Niello has double "ll" is mispronounced as "l"Remember double 'LL' in between the strings nie & o which should not be misspelled with single 'L'
Wrong Spelling:  nie-l-o  Correct Spelling:  nie-ll-o 
Find more incorrect spellings of Niello to spell right way.