Question about how to refer correctly to a certain race.?

I was treated very courteously by a salesperson who gave excellent service. The establishment had several employees working that night. I intend to call the store manager and praise that employee for her expertise and customer service skills. Unfortunately she was not wearing a name tag. Being preoccupied with my purchase I totally forgot to ask her name. I will need to describe her, and name the time and day I was in there. She appears to be African American. I am of a different race so do not know the proper term to refer to her. I fully realize many people who look like her are not in fact of African descent at all. I do not wish to appear ignorant. Unfortunately I am on this matter. I hope some one can advise me on this. I thank you most gratefully for any assistance you can give me on this. (trolls, dont waste your time, serious answers only please.) Many thanks.