Euro currency symbol "€" is being converted to generic symbol "¤"

[HamzaShamshad]

I am filling my fillable pdf with pdf-forms gem, but It is converting the euro currency symbol "€" to the generic symbol "¤".

I have tried many fonts by changing them from adobe acrobat pro like Arial, Times New Roman, Calibri, Cambria, and their Unicode supporting variants too. I have also tried changing the fonts dynamically with PDFTK and SED commands, but each time this symbol is begin changed to "¤".

This is only happening for the euro currency symbol "€" in my case (I don't know if it might happen with some other symbols) but currencies like $ work fine.