The eye colour of the Tonkinese is neither the startling amber or the chartreuse green found in the Burmese, nor is it the deep sapphire of the Siamese. It can range from aquamarine blue to greenish-blue or bluish-green. It may take some time for eye colour to settle. Tonkinese generally mature slowly, reaching their final colouring and peak size at about two years of age.
The facts presented in this Blog Post were retrieved from 'The Ultimate encyclopedia of cat breeds and cat care' by Alan Edwards, and also from the Purina website.