Get bigger wrists through training your forearms. However, your wrists won’t necessarily grow in size but your forearms will, which will make your wrists seem bigger. Your wrists are made up of mostly tendons and bones and lack the necessary muscle fibers to grow. However, the forearms connect to your wrists and they can grow in muscular size thus making you seem like you can get bigger wrists. The size of your wrists can mainly be contributed to genetic factors; small wrists are an ectomorph feature and big wrists are a mesomorph feature.

Check out this article on forearm training and what it takes for you to appear to get bigger wrists:

http://www.muscleprodigy.com/coming-to-grips-build-big,-huge-forearms-and-improve-wrist-strength-arcl-685.html