Vicuna is described as a "light neutral olive [with a Frost finish]." It's a muted, medium golden brown with a pearly sheen. It had really nice pigmentation with a blendable texture that was a smidgen powdery at times, but it was just barely powdery. This shade showed signs of fading after eight and a half hours of wear. See comparison swatches / view dupes.
FURTHER READING: Formula Overview, which is a detailed review of the range as a whole.