  The closed neighbourhood $N[v]$ of a vertex $v$ of a graph $G$, consisting of
at least one vertex from all colour classes with respect to a proper colouring
of $G$, is called a rainbow neighbourhood in $G$. The minimum number of
vertices and the maximum number of vertices which yield rainbow neighbourhoods
with respect to a chromatic colouring of $G$ are called the minimum and maximum
rainbow neighbourhood numbers, denoted by $r^-_\chi(G)$, $r^+_\chi(G)$
respectively. In this paper, by a colour, we mean a solid colour and by a
transparent colour, we mean the fading of a solid colour. The fading numbers of
a graph $G$, denoted by $f^-(G)$, $f^+(G)$ respectively, are the maximum number
of vertices for which the colour may fade to transparent without a decrease in
$r^-_\chi(G)$ and $r^+_\chi(G)$ respectively.
