The United States Department of Agriculture (USDA) grades US walnuts a bit differently compared to other foods. There are only 2 grades for shelled US walnuts: US No. 1 or US Commercial. US No. 1 "consists of portions of walnut kernels which are well dried, clean, free from shell, foreign material, insect injury, decay, rancidity, and free from damage caused by shriveling, mold, discoloration of the meat, or other means." (1) While US Commercial "consists of portions of walnut kernels which meet the requirements of U.S. No. 1 grade, except for increased tolerances." (1) A table, infographic #3 for walnut grading from the USDA website is provided below. It's a vague description for US Commercial but our interpretation is that US Commercial allows for some amount of shells, foreign material, insect injury, decay, rancidity, and free from damage caused by shriveling, mold, or discoloration of the meat where US No. 1 does not. True California will always offer US No. 1 grade only.
Interestingly enough, color plays a huge role in the quality and price of a shelled US walnut. Some walnuts are naturally darker than others, but the USDA grades walnut color by extra light, light, light amber, or amber. Please take a look at infographic #2 below. Red walnuts are extremely unique and on a scale of their own. For all other walnut varieties, extra light walnuts are the most prized and also have the highest price. The color is based on a variety of factors such as agricultural methods, irrigation, weather, and soil nutrient. True California only offers extra light and light colored walnuts.
Walnut sizes are not used for grading so much as they are for description. Walnuts come as halves, halves and pieces, pieces, and small pieces. Please take a look at infographic #1. These are based on how they've been cracked and sorted. Have the walnuts been handled carefully or just tossed into machines to be processed? The different sizes are also good for different purposes. Halves are great for snacking and small pieces are great for cooking and baking. Overall, halves generally cost more on the market because it's not easy to crack massive amounts of walnuts without breaking them into pieces. At True California, our walnuts are mostly halves with some pieces because we enjoy them for snacking first and you can always break them up yourself if you prefer.
Please take a look at the infographics below, courtesy of the California Walnut Board. We hope they help you understand more about California walnuts.