Byredo Boucle is a slightly cool-toned, dark blue with a satin finish. It is a limited edition eyeshadow.
Boucle is a deep, blackened blue with subtle, cool undertones (a "warmer" blue, if you will) paired with a pearly sheen. It had opaque color coverage that adhered well to bare skin and blended out well, but the texture was slightly firmer than is typical of shimmer eyeshadows (at this point) so it needed a slightly heavier handed approach to pick up product evenly--not too difficult or anything, and no impact to blendability. It wore well for eight hours before fading visibly on me.
FURTHER READING: Formula Overview, which is a detailed review of the range as a whole.