He's a very handsom lad Hoggy, and looks a lot like my blue girl, Pearl.
Hoggy, I don't think you can ever prove whether your boy is part-ped or not. Unless you have access to the pedigree papers of either the purported sire or dam, it's impossible to say. The trouble is that a lot of folks think that blue cats *HAVE* to be pedigree or part pedigree purely because of their colour - unfortunately that's not necessarily the case as blue is a perfectly legitimate - if not particularly common - colour for moggies.
The rarity of blue as a colour in non-pedigrees is down to the fact that it is a double recessive i.e. both parents must carry the gene for non-agouti (solid colour) AND for colour dilution. The basic non-agouti gene gives rise to a solid black, and it is a recessive of the dominant tabby gene. Blue is the dilute form of black and is far more common in pedigree cats due to the known genotypes of the parent cats and the fact that blue to blue matings will always produce blue offspring.
If you are looking for a blue cat to be a companion for your lad, you might want to look at British Shorthair, Russian Blue, Exotic Shorthair or Korat.
