You are bound by the characterset settings of the database. For example, on my local Apex installation
where my database characterset support UTF8.
SQL> select * from V$NLS_PARAMETERS
2 where parameter = 'NLS_CHARACTERSET';
PARAMETER VALUE
---------------------------------------------------------------- ------------------------------
NLS_CHARACTERSET AL32UTF8
So check with your DBA to ensure that your database characterset is set appropriately, and then your "client" (ie, the means via which you are using Apex - weblogic, ords, embedded gateway etc) also is appropriately set.