use strict;

while (<STDIN>) {
        s/[\s\(\)]+//g;         # strip optional chars
        my @matches = m/(\d+)|([^\d]+)/g;
        print join ":", grep { defined $_ and $_ !~ m/^(r|rd|red)$/i } @matches;
}

##</code><code>##

$ echo "12345 (Gray) 6789 (Red)" |  ./red.pl
12345:Gray:6789
$ echo "12345 (Gray) 6789 Red" |  ./red.pl
12345:Gray:6789
$ echo "12345Gray6789Red" |  ./red.pl
12345:Gray:6789