Some companies have dress codes written out that stipulate the types of clothes that are appropriate in that work environment and subsequent penalties if the code is not followed (ie. sent home without pay until appropriate attire is worn). If your company has such a dress code (one that is formalized and written out), then a reminder email to all staff about dress requirements, with the actual dress code document attached, may help.

If that doesn’t work, a colleague (I’d suggest a female colleague) take her aside and let her know of the document and that she may want to look it over so not to be reprimanded “officially” (again- sent home without pay).

However, if there is no document that outlines required dress (no formalized company code = no violation) then that’s a bit trickier. In this case, it’s more likely left to the opinion and discretion of the individual – and those opinions can vary dramatically from culture to culture. Since I don’t know anything about the particular issue that you’re referring to, it’s difficult to respond (ie. whether or not she reports to you, she’s a colleague, if your company has a human resources department which could handle the “situation”)

Using the wording from the example in the above post, you could substitute words for your particular situation without saying “you’re exposing too much skin.” You could say, “I know you work very hard to ensure all your assignments are done to the best of your ability and you’d probably like to know if there’s something that, despite your good work, may distract others from your abilities. I believe that I should let you know that you need to pay more attention to creating a professional look in the way that you dress.”

You could have some pictures of the type of dress that would be more suitable and point out the length of the skirt and the blouse’s collar and how it is buttoned, suggesting that she would be perceived as more professional dressed this way. If she asks for specifics about the way she already dresses, focus on what she can do instead of how she is looking. You could easily say “Even just doing up the top couple of buttons on your blouse would give a more professional impression,” or “choosing a more closed neckline would suit a professional image better.”