Ian,  What you describe sounds like a Pathe ball sapphire stylus for
playing the Pathe hill and dale records.  You cannot play Edison
Diamond Discs or regular 78 records, for that matter, with the Pathe
ball stylus -- it is too big to fit the fine grooves of an Edison
record.

If this Balance reproducer is adjustable you should be able to play
Pathe and regular 78 rpm records just by changing the position of the
reproducer and using the ball stylus for Pathe records and steel needles
for 78 rpm records.

Don't try to play Edison records with a steel phonograph needle, it
will damage them.  Really the very best thing to play an Edison Diamond
Disc with is an Edison reproducer.

Michael Swanson