Honey is graded (A, B, C) according to the amount of soluble stuff (chunkies like pieces of the comb, pollen, etc), "absence of defects (again having chunks of stuff floating about), flavor and aroma (not caramelized, not fermenting, not smoky tasting), clarity (amount of air bubbles, particles that might affect appearance). Moisture content is also a big part; apparently it doesn't seem to be a factor considered during USDA grading but when honey is being judged at a fair the honey can't have too much moisture (or too little). Honey is hygroscopic, meaning that it has a tendency to absorb moisture if you live in a humid environment or lose moisture to the air if it is very dry. So maybe the crystallization you see might be due to the honey losing moisture (maybe the particular honey you see crystallizing is lower in water content???) Filtering also removes particles from the honey that may instigate crystallization; so filtering quality may also play a part. Apparently adding a quarter to half a tablespoon of cream of tartar per pint honey helps prevent crystallizing. If you are interested, check the next URL for more information.

thriftyfun