I've always been partial to this "description" of BJJ that is posted in our academy...
White Belt-You are just learning the words. You do not always fully understand them, but you are starting to build a vocabulary. You can sometimes get your point across with a single word, or two strung together, but that is usually by accident.
Blue Belt-You have built up your word vocabulary, and are starting to use sentences. They are not always well punctuated, and are most often very simple. You are starting to notice the intricacies of those who write well, but are not yet able to match their abilities.
Purple Belt-You have a good understanding of how sentences are put together, and are finding ways to say the same thing using different approaches. You are working on proper grammar, and can now start to put together well structured paragraphs. Your individual style is also starting to come through.
Brown Belt-Your style and writing ability are very well established. You are more than capable of writing a book.
Black Belt-Poetry.