my guess then would be that she is not borderline.....but i dont know her soo. i have got friends who are borderline, one whom i posted about here last year lol. she is so imo very typically borerline and i have ad to mostly cut contact wiht her to mantain my own mental health.
does ur colleague know that u know she cuts? if she does maybe u could manage to let her know that if she wants to talk or nything she is welcome to come to u, she mite well tell u wat if ny dxes she has been given.
most borderline pts (imo) are pretty much unabe to function well, cant hold down jobs, cant deal with people without having arguments and hating them etc etc.
it is highly possible she suffers from plain old depression, or has in the past, and discovered si as a coping mechanism. it can be very hard to let go of a coping mechanism that works when all else seems to fail.
i would say if her supervisor is aware of her cutting he is keeping an eye on her and if she was to start being not "normal" would soon suggest she had time of.got treatment again etc.
let us know how things go
its nce to hear about someone who has difficulties and is functioning in a stressful job
im not getting across wat i want to well sorry.
there are a few good threads in this forum with a wealth f info about bpd.