I love how this painting is so detailed that you an see the golden designs on her clothing look like cheap ironed on patches as they fray out into the air on the edges. On closer inspection, it almost looks as if the white layer is a separate garment entirely to the designs on top.
They are in fact very expensive, sew-on patches. They’re embroidered by hand on separate fabric, and then sewn on the dress. It’s a hell of a lot of work. The gold work here looks like a specially woven brocade (woven with actual precious metals)
The edges are finished with cording (stitching over the edge) to prevent the fabric from fraying. They would eventually wear out though, but since each piece is so expensive, they’d wear them for a long time. And since these pieces were often made with literal gold and silver, they’d be removed from clothing, applied to new clothes and we’re often heirlooms.
I have seen this kind of works from close-up. Our neighbor was a master parament stitcher (not sure if this is the correct English term), and she had some awesome works in her flat. Including her masterpiece, a Madonna stitched with dozends of different techniques.