If they'll do it at all I'm sure it depends on the stone.
To protect themselves they probably require it to have a grading report from a reputable lab like GIA or AGS because their clarity grades can be believed.
Next they'd need to verify it still matches the report and has not been damaged since the report was issued.
Next, they have to consider it to be mechanically stable enough to be set ...
A diamond with many large feathers, the diamond industry's pretty word for cracks, that reach the surface may be declined.
Next it may be against their policy for business reasons.
Maybe they'll do it but take no responsibility if the stone fails or is damaged by setting it.
Re: Can WF or BGD set your personal diamond in their setting
The first setting I fell in love with was in the WF gallery. I contacted them to find out about the cost of getting it made and was informed that they would not make it for me unless I bought a stone from them. At the time I was very disappointed as I had planned on that setting never even imagining or considering that they would require me to buy the stone from them as well.
In my mind, the setting is secondary to the stone. In the end, WF did me a favor as I have a one-of-a-kind treasure made just for me and not just a duplicate of someone else's ring, albeit beautiful. HPD did an exquisite job turning my ideas into reality and I'm more than satisfied with the way things turned out.
Re: Can WF or BGD set your personal diamond in their setting
I sent a ring with a .55 ct diamond to BGD. They took the diamond out, set it in a pendant and returned the ring setting to me. It was very easy and I'm so happy I did it. I didn't wear the ring before and now have a gorgeous necklace I wear all the time.