The Essentiel Antwerp Hemethyst Sequin Buttondown Blouse is a crisp cotton-poplin shirt with a preppy collar, relaxed dropped shoulders, and playful sequin and bead embellishments for a touch of whimsy. The Essentiel Antwerp Hemethyst Sequin Buttondown Blouse is a crisp cotton-poplin shirt with a preppy collar, relaxed dropped shoulders, and playful sequin and bead embellishments for a touch of whimsy. After launching a successful T-shirt collection that quickly took over their apartment, husband-and-wife designers Esfan Eghtessadi and Inge Onsea opened their first boutique in Antwerp, Belgium in 2000. Today, Essentiel Antwerp is a complete ready-to-wear line marked by playful prints, pop colors, and spot-on detailing.