Why dont you ask her? Has she tried on some .75 and some 1 carat stones? I think she needs to try some on and let you know what is
the smallest she thinks will be appropriate for work.
Here is a relative size difference between a 1 carat and a .75 on a 4.25 finger.
I think i will go for 0.80ct I color (AGS) and set it in 18k rose gold ring & platinum prongs.
We have an I color bezel pendant and it looks pretty white. If we get another I color and set it in 18k rose gold, do u think it will look more warmth than the pendant?