Unicode characters in records

If I am having a good day, I can barely spell unicode. We are in the process of upgrading our application to support unicode characters.
CREATE TABLE LOOKUP
(ID NUMBER,
DESC VARCHAR2(320));
This table exists in a 10GR2 database that supports UTF-8.

How do I query the databse to return all the IDs where DESC contains 1 or more unicode (non-ASCII) characters?

TIA!

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