Resembles possibly the Ussuri cat. (a breed some russian breeders try to establish...). I have seen only a couple of photos on them . difficult to find - but they do look something like that....
Talk over the owner to show this "mini-coughar". Almost all cat shows do have also a class for non breed cats. It is of course necessary the cats accept the milieu...
Just becasue a cat is color point and blue eyes, doesn't make it a Siamese or a Siamese mix. The color point gene is recessive and can be in any cat's background if you go back far enough.
I don't assume there is a Siamese in there in the first few generations - just that its a color point mixed breed cat.