Nial - basically you want a good contrast between the base color and the spots (btw the spots are formed on the surface of the coat. When you flip the coat back they look like the ticking of an Aby)
The spots should form a sorta bullseye pattern on the sides about in the middle toward the back. Head should be slightly long, muzzle strong and squarish - not a pointed like a Siamese. Ears are tall and should be set at a 45 degree angle. You want width between the ears but the ears still have to be 45 degrees. Eyes almond shaped. And broken necklaces in front.
He has a good tight body, good muscle and balance on the head. Charlie's ears are a little taller but if you compare the picture of Charlie in my signature, you can see Jack will have a lot better ear set.
His dad has excellent contrast (dad is a cinnamon) and he really looks a lot like dad.
BTW have you contacted Sonja yet for your Oci?