Thiewes was born in Owatonna, Minnesota, and attended a private Catholic school, where she derived some inspirations for her work. She received her BA in Art/Metals from Southern Illinois University, Carbondale, and her MFA in Art/Metals from Kent State University. Thiewes began teaching at the University of Texas at El Paso in 1976 and is a current member of the Society of North American Goldsmiths. She also taught a Master class at the Royal College of Art in London in 1995.
Her work is displayed in many art collections across the world, including The Metropolitan Museum of Art, The American Craft Museum, The Art Institute of Chicago, The Renwick Gallery at the Smithsonian Institution, The National Museums of Scotland, and the Royal College of Art, London.