Your heart was in the right place, but jumping to conclusions based on one observation is a bad idea

To be fair, you could be right and she could just be uncomfortable telling you so. But you opened the door for further conversation, so hopefully if she does have a self-harm problem she will feel a bit more comfortable talking to you about it later. In the meantime, don't walk on eggshells around her, just treat her nicely and like everyone else. You have a good heart, OP.

Another thought: it can be really embarrassing when people ask you about your scars or tell you to stop harming (speaking from experience). A better approach might be just to tell her that you're there for her to talk to and that you hope that she doesn't need to injure herself anymore.

It's amazing that you care and offered to help, even if it did become a bit awkward with your co-worker

Never assume the worst. I'm surprised she didn't smack you upside the head for that. I would have done a Gibbs smack.

When you assume you make an ASS out of U and ME. Remember that and maybe you'll avoid situations like this again. However, like others have said, you're heart was in the right spot.

While I admire the fact that you were trying to help, you probably should have considered asking her if there was something going on before assuming she was cutting herself.

Like other said your heart was in the right place, but it could have been worded differently. Ive got scars on my arm that Ive done, unfortunately my daughter does too, as do a couple other people I know. Ive had a supervisor who had some scars on her arms that looked like they were self inflicted - she told us she was in a serious car accident that nearly cost her her life. Dont be quick to assume scars are self inflicted - if you were quick to judge me like that Id deny them, Ive had people ask, and depending how I felt about you I may (or may not) rell you I was ill. To this day I fight the urge, but dont need the assumption. Hope your coworker eventually may be comfortable opening up IF it is self inflicted, it may be just her being clumsy. God knows Im like that - I almost fell into a deep freezer at work last week lol it happens

As someone who used to self harm, it actually makes me really uncomfortable when someone points out my scars and then my confidence is gone for the rest of the day

Its good to be so caring, although, Scars are different from fresh cuts, self harmers often hide scars and cuts, if a self harmer has visible scars they may no longer be harming and to be a recovered self harmer and have something as ashaming as that mentioned can hurt, to have to explain the same thing a million times isn't easy, most recovered self harmers already have a support network and having every new person you meet offer to do the same is very endearing but can also make you feel like a freak. Side note: It is awesome to offer help and support to someone in trouble and this doesn't happen enough for some people.