I love
Jocelyn.
Jo as a nn of
Jocelyn is fine. I pronounce it as "JOS-u-lin", not "JAHS-u-lin" like it says here - I think that's just an accent thing as JAHS-u-lin sounds American English to me.
What about
Jocasta and
Jolanda?
Here are
Jo- names:
http://www.behindthename.com/php/search.php?terms=jo*&nmd=n&gender=f&operator=or
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My 45 PPs - names in profile