What do HB B 2H signs in pencils mean?

Those signs stand for the different kinds of hardness there are and the resultant shade difference of the pencil.

H (2H, 4H, etc) are the harder leads, and therefore draw a lighter line; and B (2B, 4B, etc) are the softer leads, and therefore draw a darker line. HB is the designated centre of the range. The larger the number, the farther away from HB it is. So for instance, 6B will be darker than 2B, and 4H would be lighter than 2H.

KOH-I-NOOR HARDTMUTH, the company, was the originator of this gradation system. Originally established by Josef Hardtmuthin 1790, it produced stoneware and building materials, because Hardtmuth was a very proficient architect and builder. Hardtmuth was a typical inventor, he developed several types of building material and stoneware and even the modern lime-sand brick and the technology for its production. His profession placed great requirements on drawing. However, the drawing tools at that time were only the handmade, and therefore very expensive and not readily available, English pencils or unsatisfactory German pencils, both made of a single piece of graphite. Hardtmuth combined his knowledge and technologies used in building materials manufacturing and developed a pencil lead based on a mixture of clay and ground graphite along with the revolutionary technology for series production. The basis of this technology is still used by all pencil lead manufacturers worldwide.

Beginning of Gradation of Graphite Pencils

Over time, manufacture of pencil leads and pencils became more important than production of stoneware and building materials, so a completely new factory was built in 1848 in České Budějovice. Franz, the grandson of Joseph Hardtmuth, was also a skilled engineer who fundamentally improved production technology and assured transition from a manufacturer to fully industrial and effective production methods with a guaranteed high quality. Gradation graphite pencils and the first 12 coloured leads, followed by the black dry velvet Negro lead, saw the light of the world for the first time as a result of innovations by Franz Hardtmuth. Graphite pencils were initially produced in 17 grades under sequence number 1500 and because the outside was a shiny yellow, they were named "KOH-I-NOOR" after the famous yellow diamond. Immediately after production was launched this 1500 pencil became a worldwide sales success and is still made today in 20 grades under the same identification and name. The name KOH-I-NOOR was combined with the family name of Hardtmuth as the name of the whole company: "KOH-I-NOOR HARDTMUTH." The whole grading system was subsequently described using the letters H, B and F - the first letters of the names Hardtmuth, Budějovice and Franz. This grade identification system was also adopted worldwide. During the 20th century, the marking system went on to be redefined.