this question is for the ladies out there.. :)

[TC1987]

Probably the diamond should be insured from the moment that you receive it, unless you don't plan to ever insure it. There used to be issues with companies refusing to insure unset / unmounted diamonds. If that's still the case, you should have it set in an inexpensive mounting of some sort, rather than use a stone holder. It's probably best to let her choose the permanent setting, or both of you choose it together.