If you have problems with inserting special-characters into Tables using UTF8,
maybe because the SQL-File, containing the insert is not in UTF8 then you can use the function unistr(),similar as chr().

Example of ‚ô‘ SMALL LETTER O WITH CIRCUMFLEX‘ (U+00F4)
select unistr(‚\00F4′),’CA‘ from dual;

Oracle docu for UNISTR()

A list of UTF8-Characters-Codes can be found here