I have had my eye on these barrettes (especially the thin one in gold) by Sylvain Le Hen for so long. It's the most perfect minimal hair accessory; so sleek and elegant. I was excited to pick one up at Colette and I wore my hair half up / half down most of my time in Paris. It was even here in the photo below at the Tuileries, that a french man asked me for the time - thinking I spoke french and surprised that I didn't. Must've been the stripes, barrette and loafers. Must've.

Sylvain Le Hen Barrette available here and here.