I think you’re really close to completing a rainbow colored collection. As in just the basic rainbow colors....Red, Orange, Yellow, Green, Blue, Indigo & Violet. Any other shades like the MBH Ambassator, glen blue, cado & lime should be in this rainbow too and you already have most of them.
Black isn’t a color of any rainbow so any kettle that has speckled black should be excluded.
I think all you’re missing is an Orange color MBH and we all know those are hard to find and tougher to aquire.
Or if trying to catch em’ all..... use this check list