The first graphite grading scale is numeric. Using this scale, the hardness of the core is often marked on the pencil — look for a number (such as “2,” “2-1/2,” or “3”). The higher the number, the harder the writing core and the lighter the mark left on the paper. As the pencil core becomes softer (using lower proportions of clay), it leaves a darker mark as it deposits more graphite material on the paper. Softer pencils will dull faster than harder leads and require more frequent sharpening. The second graphite grading scale is known as the HB scale. Most pencil manufacturers outside of the U.S. use this scale, using the letter “H” to indicate a hard pencil. Likewise, a pencil maker might use the letter “B” to designate the blackness of the pencil’s mark, indicating a softer lead. The letter “F” is also used to indicate that the pencil sharpens to a fine point. Historically, pencil makers also use combinations of letters to tell us about the Graphite — a pencil marked “HB” is hard and black, a pencil marked “HH” is very hard, and a pencil marked “BBB” is black! Today, however, most HB system pencils are designated by a number such as 2B, 4B, or 2H to indicate the degree of hardness. For example, a 4B would be softer than a 2B and a 3H harder than an H. Generally, an HB grade about the middle of the scale is equivalent to a #2 pencil using the U.S. numbering system. In reality, however, there is no specific industry standard for the darkness of the mark to be left within the HB or any other hardness grade scale. Thus, a #2 or HB pencil from one brand will not necessarily leave the same mark as a #2 or HB pencil from another. Most pencil manufacturers set their internal standards for graphite hardness grades and the overall quality of the core; some differences are regional. Consumers prefer softer, darker leads in Japan, so an HB lead produced in Japan is generally softer and darker than an HB from European producers. If you are looking for high quality, high purity, and cost-effective Graphite, or if you require the latest price, please feel free to email contact mis-asia.