This hummingbird resembles the Madeira hummingbird (Eulampis jugularis), the largest hummingbird in the Lesser Antilles. Present in Martinique, it measures about 4.3 to 4.7 inches (11 to 12 cm) and weighs 0.24 to 0.4 oz (7 to 12 g). Black in color with many iridescent reflections, it has a deep red throat. All hummingbirds have more or less extensive areas of shimmering colors, often concentrated on their throat, wings, and head. These colors with metallic reflections are due to the diffraction of light rays produced by the particular microstructure of the cells of the feathers. Depending on the angle of the light, the wavelengths are intensified and the iridescent feathers appear vibrant or remain dark and dull. The hummingbird has a very large number of feathers in relation to its weight, around three hundred per gram.