Related to smoke, Siamese creates a darker or lighter marking which makes the face have a mask, and colors the tips of all the limbs. Mask is only needed minimum amount for the marking. Not all the limbs has to be colored. If the mask is hidden by another marking, it has to show on some other point.
In it's dominant form extends more to the body.
The mask has to be hard or slightly soft edged, it cannot be fully gradient. Siamese mask can contain tiny amount of rugged texturing on the edge, including small patterns. This amount however is very small, as minimum amount of mask is required to always show without changing its placement radically. Siamese will never be able to do job meant for painted.
The diagram above shows the maximum extent of siamese on a kuku's face. You can however create the illusion of the mask extending to the ears by colouring the ears the same colour; as long as you follow the coat colour rules it should be fine.