These questions of acceptability are always tricky. The standard reply is, as you are probably aware, that if you have to ask, it is probably at least borderline. Keep in mind that the final answer may hinge upon details you have not provided, such as your position within the firm, the general attitude you attempt to portray through your choice of dress, the peculiarities of your particular co-workers. Ultimately the most important issue is this: Will you feel comfortable in them in such an environment? If the answer is no, then even if your co-workers are accepting, the self-doubt you will have created with regard to the shoes is fatal. My personal answer is that the shoes are acceptable. I would pair them with an otherwise conservative outfit, especially at first. The pairing you suggest is timelessly elegant, and so I susect that your apparently daring color choice will not be so shocking to the conscious as to endanger your professional career. Go for it.