[1] R. plumbicolor is stout and viper-like in body structure, and about 2 ft (61 cm) in total length (including tail) when fully grown.

There are 7 scales on the upper lip (supralabials), the third and fourth touch the eye; and 4 or 5 lower labials in contact with the anterior chin-shields, which are shorter than the posterior.

R. plumbicolor is dull green above, uniform or with traces of black markings.

[2] Young specimens show an inverted black V-mark on the neck, its apex forwards, reaching to the frontal shield, and a second much smaller one behind, the intervening space being bright yellow or orange; a black stripe from the eye to the angle of the month, and more or less regular transverse spots or cross-bars on the back and tail; belly whitish, yellow or plumbeous, rarely with darkish spots.

[3] R. plumbicolor is found in peninsular India and Sri Lanka especially on the hills rather than on the plains.