Hi all,

The original internal ring diameter is 16.45mm. I need to up it to 17.5mm without changing the gemstone dimensions and keeping the ring shank dimensions
the same. The yellow line indicates the new size of 17.5mm.



Please could someone explain how I can do this? I need this asap so if anyone can chime in, I'd be very appreciative. I have attached the original file as well.

Many thanks!!
Gunter