Why use different pencils? What are pencils

Decide what you need pencils for.

• What are you going to do with the pencil? Will you write a lot? Or do homework? How about solving crossword puzzles? Or do sketches and draw full-fledged paintings?
• How much pressure do you use on the pencil when writing or drawing?
• Do you prefer a thin line or a thick one?
• Do you tend to regularly lose pencils, give them to others, chew them or spoil them, or do you try to save pencils and keep them exclusively in a pencil case?
• Do you carry pencils in your pocket, at the risk of injuring yourself with the tip of the lead?
• Do you try to keep the eraser on your pencil, or does it tend to get lost? Do you rarely use an eraser and it just dries out?

Pay attention to what you like or dislike about the pencils you use. Perhaps some are very comfortable to hold in your hand, while others, on the contrary, are difficult to move across a sheet of paper.

Think what you like best: mechanical pencil or traditional.

• Mechanical pencils do not need to be sharpened, but they do require replacement of the correct lead thickness. As a rule, when about 1 centimeter remains from the stylus, it can no longer be used.
• Mechanical pencils allow fine, even lines to be drawn, which may be advantageous when creating technical drawings or small drawings.
• The length of a mechanical pencil does not change over time.
• Mechanical pencils are usually more expensive than traditional ones, especially high-quality ones designed for long-term use. Most often, in mechanical pencils, it is possible to replace the lead and eraser, which allows you to use it for a very long time.
• Regular pencils are usually cheap. The thickness of the line may vary depending on the angle of inclination and the degree of dullness of the lead.
• The advantages of conventional pencils are their low cost, availability and ease of use. Many also like the feel of using a regular pencil.

Practical tasks in engineering graphics

Drawing lines and fonts

Graphic Work No. 1

Graphic work № 1 , recommended for students to perform engineering graphics, aims to master the skills of drawing drawing lines, fonts and inscriptions, as well as to get acquainted with the basics of working with a compass.
In the process of doing the work, the student must complete the frame of the drawing, the main lines provided ESKD, drawing font letters, and circles represented by various drawing lines.

The work is done on drawing paper A3 (420×297 mm).
To complete the work, you will need pencils with hardness TM ,T , 2T , a ruler with a length of at least 300 mm, a protractor, a compass, a square (to perform auxiliary parallel lines) , eraser, pencil sharpener.
Ruler and square must be wooden or plastic (metal ones strongly “cut” the pencil lead, leaving dirt on the drawing).

For high-quality graphic work, it is necessary to have a set of pencils, which must necessarily include a pencil of medium hardness ( TM ), solid ( T ) and very hard ( 2T ). Wherein hard pencils are used to draw thin lines in the drawing and for a preliminary sketch of the outline of the image, which is subsequently outlined with a medium-hard pencil.
Marking of pencils adopted in different countries, described below.

Designation of pencil hardness

In different countries, the hardness of pencils is marked with different symbols.
In Russia, the marking of pencils with letters has been adoptedM (soft) andT (solid) or combinations of these letters with numbers and with each other. The numbers in front of the letter are an indication of the degree of hardness or softness of the pencil. At the same time, it is intuitively clear that2M - very softM – soft pencil, TM - a pencil of medium hardness (hard-soft),T - solid and2T - a very hard pencil.

There are often imported pencils on sale, for which European or American markings are used.
In the USA, pencils are marked with numbers from 1 to 9 (fractional numbers are also used, for example: 2.5), while the number is usually preceded by a # (pound sign):#1 , #2 , #2,5 , #3 , #4 etc. The larger the number (number) in the marking, the harder the pencil.

The European marking of pencils is based on the letters of the Latin alphabet:

· B (short for blackness - blackness) - corresponds to the Russian marking under the letterM (soft);

· H (from hardness - hardness) - corresponds to the Russian hardness markingT (solid);

· F (from fine point - subtlety, tenderness) - a pencil of medium hardness, approximately corresponds toTM . However, the combination of lettersH AndIN – HB also indicate the average hardness of the pencil.

European marking provides for a combination of lettersIN AndH with numbers (from 2 to 9), while, as in the Russian marking, than more figure, the higher the property of the pencil corresponding to the letter (softness or hardness). Pencils of medium hardness according to the European marking have the designationH , F , HB orIN .
If there is a letter on the pencilIN with a number from 2 to 9 (for example:4V , 9V etc.), then you are dealing with a soft or very soft pencil.
LetterH with a number from 2 to 9 on a pencil indicates its increased hardness (for example,2H , 7H and so on.).

Graphic work task №1 and a sample of the work performed are shown in the figure below.
A full-size sample of the work can be opened in a separate browser window by clicking on the picture with the mouse. After that, it can be downloaded to a computer or printed on a printer for use as a task for students.
The task is presented in two versions:

· Option number 1

· Option number 2

The task is aimed at acquiring and improving the skills of drawing lines of a drawing and fonts, while their style must comply with the requirements stipulated by the standards ESKD And ESTD.

As required ESKD the dimensions of lines and fonts in the drawing must meet the following requirements:

· main solid thick line (for drawing a frame, title block, outline of a part or assembly - that is, the main lines of graphic work) should be thick 0.6...0.8 mm; on large drawings, this line can reach 1.5 mm in thickness.

· dashed line (draw lines of an invisible contour)- made thick 0.3 ... 0.4 mm (i.e. twice as thin as the main thick line). Stroke length (4-6mm) and the distance between adjacent strokes (1-1.5mm) normalized GOST 2.303-68;

other lines (dash-dotted, wavy, solid fine - to designate axes, extension and dimension lines, section boundaries, etc.)- thick 0.2 mm (i.e. three times thinner than the main thick solid line) .
The length of the strokes in the dash-dotted line (designation of axes) should be 15-20 mm, the distance between adjacent strokes - 3 mm.

· letter height fonts must correspond to the ruler allowed by the standard, while the height of lowercase letters and the distance between letters in a line correspond to the size of uppercase (capital) letters.
Most often in graphic works of the format A4 And A3 fonts like IN with tilt angle 75 degrees, while the height of lowercase letters (which should be equal to 7/10 of the height of uppercase i.e. capital letters), is taken equal to 3.5 or 5 mm (respectively, the height of capital letters is 5 or 7 mm).

· Letter spacing line should be equal to 1/5 capital height (capital) letters, i.e. for height capital letter 5 mm spacing between letters in a string - 1 mm, for capital letter height 7 mm- spacing between letters 1.5 mm .
When writing letters, it is important to keep them the same height and slope in the line, as well as the distance between adjacent letters.

Pencils are an amazing tool that is used for drawing and drawing work. In order for the work to be successful, it is important to know everything about the characteristics of this tool. It is necessary to figure out what they are, what is the decoding of the hardness of a pencil lead and what effects can be obtained when using tools with different characteristics.

Varieties of pencils

Pencils are divided into two large groups: colored and graphite (simple). They, in turn, are divided into varieties. Let's consider each of them in more detail.

Classification of colored instruments:

• Colored. These are the most common tools that everyone used to draw at school. There are hard, soft, soft-hard.
• Watercolor. After painting, they are blurred with water to obtain a watercolor effect.
• Pastel. These are pastel crayons in a wooden frame. They are very soft. They are convenient because they do not get your hands dirty, they are protected from frequent breaking of crayons, and they also have a standard size.

Classification of tools with graphite rod:

• Simple. Just they are most often used in graphics (drawing with pencils). They have many different markings, we'll talk more about them later.
• Coal. They are pressed charcoal for drawing in a wooden frame. The benefits are the same as for pastels.
• Conte. They are almost the same as pastel, but have a different color palette: there are black, gray, brown and other shades. There is also white in the range of colors.

How to determine the hardness of pencils

Now let's take a closer look at the graphite type. They can depict anything, and very realistically. The works are “alive” thanks to shading, the correct overlay of tone, the right pressure on the tool. Therefore, the whole drawing or drawing as a whole depends on its quality and number.

The scheme is great for determining the hardness of pencils. A table would also work. To visualize and determine the density, you can use the pencil softness table, as well as determine the hardness on a special scale. By the way, you can draw such a scale yourself. To do this, you need to take all the tools that you have and alternately shade small sections of paper with them: from the darkest to the lightest, or vice versa, there will be an H. B marking in the middle. Thanks to this scheme, it will be easy to navigate and remember the type of instrument.

Markings and their meaning

First of all, you can see both English and Russian designations for the hardness of pencils. Let's take a look at both types:

Often, in addition to letters, markings contain numbers that show the strength of hardness or softness and tone. For example, there are 2B, 3B, 4B, 5B, 6B, 8B pencils. 2B is the lightest, 8B is the darkest and softest. The digital marking of hard pencils looks similar.

Applying tone to a drawing

Tone mapping rules are very important when drawing. This is especially true for graphics, because in it the work is created exclusively in one scale: black or gray in combination with white additions.

Pencils They differ mainly in the type and nature of the writing rod (which determine the writing properties of the pencil and its purpose), as well as in size, cross-sectional shape, color and type of wooden shell coating.

Since the 1950s, pencils have been produced in the USSR in accordance with GOST 6602-51. The quality was good. The current situation is rather sad. Let's talk about what happened before.

Pencils

Depending on the writing rod and its properties, the following main groups of pencils are distinguished: a) graphite - the writing rod is made of graphite and clay and impregnated with fats and waxes; when writing, they leave a line of gray-black color of varying intensity, depending mainly on the degree of hardness of the rod; b) colored - the writing rod is made of pigments and dyes, fillers, binders and sometimes fats; c) copiers - the writing rod is made from a mixture of water-soluble dyes and a binder with graphite or mineral fillers; when writing, they leave a gray or colored line, difficult to cut with an elastic band.

Stages of production of pencils from glued boards

Production of pencils consists of the following main processes: a) the manufacture of the writing core, b) the manufacture of the wood shell and c) the finishing of the finished pencil (coloring, marking, sorting and packaging). The composition of graphite rods includes: graphite, clay and adhesives. Graphite is very graded and leaves a gray or grey-black streak on paper. Clay is mixed into graphite to bond its particles, and adhesives are added to the graphite-clay mixture to impart plasticity. Screened graphite in vibratory mills is crushed to the smallest particles. Clay is soaked in water. Then these components are thoroughly mixed in special mixers, pressed and dried. The dried mass is mixed with adhesives, repeatedly pressed, turning into a homogeneous plastic mass suitable for molding writing rods. This mass is placed in a powerful press, which squeezes out thin elastic threads from the round holes of the matrix. Upon exiting the matrix, the threads are automatically cut into segments of the required length, which are the writing rods. The segments are then placed in rotating drums, where they are rolled out, straightened and dried. After drying, they are loaded into crucibles and fired in electric furnaces. As a result of drying and firing, the rods acquire hardness and strength. The cooled rods are sorted by straightness and sent for impregnation. This operation aims to give the rods, which after firing increased rigidity, softness and elasticity, i.e., the properties necessary for writing. For the impregnation of graphite rods, lard, stearin, paraffin and different types wax. For the manufacture of color and copy rods, other types of raw materials are used, the technological process is partially changed.

For colored rods, water-insoluble dyes and pigments are used as colorants, talc is used as fillers, and pectin glue and starch are used as binders. The mass, consisting of dyes, fillers and binders, is mixed in mixers, the firing operation falls out. The strength of the colored rod is given by the pressing mode and the regulation of the amount of binders introduced into the mass, and this, in turn, depends on the nature and amount of pigments and dyes. For copy rods, water-soluble aniline dyes are used as dyes, mainly methyl violet, which gives a trait when moistened. purple, methylene blue, giving a line of greenish-blue color, brilliant green - bright green, etc.

The strength of the copy rods is regulated by the recipe, the amount of binder and the pressing mode. Finished rods are placed in a wood shell; wood should be soft, have low cutting resistance along and across the grain, have a smooth, shiny cut surface and even tone and color. best material for the shell is the wood of the Siberian cedar and linden. Wooden boards are treated with ammonia vapor (to remove resinous substances), soaked in paraffin and stained. Then, on a special machine, “paths” are made on the boards, into which the rods are placed, the boards are glued and divided into individual pencils, while giving them a hexagonal or round shape. After that, the pencils are ground, primed and painted. Painting is done with fast-drying nitrocellulose paints and varnishes, which have a clean tone and bright color. After repeated coating of the shell with these varnishes, a strong varnish film is formed on it, giving the finished pencil a glossy, shiny surface and a beautiful look.

Classification of pencils

Depending on the source materials of the writing rod and the purpose, the following groups and types of pencils are distinguished.

1. Graphite: School, Stationery, Drawing, Drawing;

2. Color: School, Stationery, Drawing, Drawing;

3. Photocopiers: stationery

In addition, pencils differ in overall dimensions, in the hardness of the core, and in the finish of the shell. Dimensional indicators include: cross-sectional shape, length and thickness of the pencil. According to the shape of the cross section, pencils are round, faceted and oval. Some groups or types of pencils are assigned only one cross-sectional shape; for others, different ones are allowed. So, drawing pencils are produced only faceted - hexagonal, copying pencils - only round; stationery can have any of the indicated shapes, as well as a three-, four-, octahedral or oval cross-sectional shape. The pencils are 178, 160, 140 and 113 mm long (with a tolerance of ±2 mm for these dimensions). The main and most commonly used of these sizes is 178 mm, it is mandatory for graphite pencils - school, drawing and drawing; for color - drawing and drawing; for stationery colored pencils, a length of 220 mm is also allowed. The thickness of a pencil is determined by its diameter, and for faceted pencils, the diameter is measured along the inscribed circle; it ranges from 4.1 to 11 mm, the most common thickness is 7.9 and 7.1 mm.

According to the degree of hardness writing rod pencils are divided into 15 groups, designated by letters and numerical indices in sequential order: 6M, 5M, 4M, 3M, 2M, M, TM, ST, T, 2T, ZT, 4T, 5T, 6T, 7T. The letter "M" denotes the softness of the writing rod, the letter "T" - its hardness; the larger the digital index, the stronger this property is for a given writing rod. At school graphite pencils the degree of hardness is indicated by the numbers No. 1 (soft), No. 2 (medium) and No. 3 (hard). On carbon pencils - in words: soft, medium hard, hard.

Abroad, the degree of hardness is indicated with Latin letters"B" (soft) and "H" (hard).

Graphite school pencils were produced in medium hardness, drawing pencils - of all existing degrees of hardness, colored pencils of all types - usually soft.

Graphite drawing pencils "Designer"

The color of the wood shell coating is also different for different pencils; the shell of colored pencils, as a rule, was painted according to the color of the writing rod; for the shell of other pencils, each title was usually assigned one or more permanent colorings. The color of the shell was of several types: one-color or marbled, decorative, with ribs or edges painted in contrasting colors or covered with metal foil, etc. Some types of pencils were produced with a decorative head, which was painted in colors different from the color of the shell , with a plastic or metal head, etc. Pencils with plastic or metal tips, with an elastic band (only graphite), with a sharpening of the rod, etc. were also produced.

Depending on these indicators (properties of the writing rod, cross-sectional shape, overall dimensions, type of finish and design), different names were assigned to each type of pencils and sets.

Graphite drawing pencils "Polytechnic"

Assortment of pencils

Pencils are divided into three main groups: graphite, colored, copying; in addition, there is a special group of special pencils.

Graphite pencils by purpose are divided into school, stationery, drawing And drawing.

School pencils - for schoolwork in writing and drawing; three degrees of hardness were produced - soft, medium and hard - designated respectively by numbers: No. 1, No. 2, No. 3.

Pencil No. 1 - soft - gave a line of thick black and was used for school drawing.

Pencil No. 2 - medium hardness - gave a clear black line; used for writing and drawing.

Pencil No. 3 - hard - gave a pale line of grayish-black color: it was intended for drawing and initial work on drawing at school.

School pencils included pencils that had a metal nipple in which a rubber band was fixed to erase notes made with a pencil.

Stationery pencils - for writing; produced mainly soft and medium hardness.

Drawing pencils - for graphic works; produced according to the degree of hardness of the writing rod from 6M to 7T. Hardness determined the purpose of the pencils. So, 6M, 5M and 4M are very soft; ZM and 2M - soft; M, TM, ST, T - medium hardness; ST and 4T - very hard; 5T, 6T and 7T - very hard, for special graphic works.

Drawing pencils - for drawing, shading sketches and other graphic works: only soft ones are produced, various degrees hardness.

Assortment of graphite pencils

colored pencils according to purpose are divided into school, stationery, drawing, drawing.

School pencils - for elementary child drawing and drawing works of schoolchildren lower grades ; were produced in round shape, in sets of 6-12 colors.

Stationery pencils - for signature, proofreading, etc., 5 colors were produced, sometimes two-color - for example, red-blue, mainly hexagonal, except for Svetlana pencils, which had a round shape.

Drawing pencils - for drawing and topographic work; produced mainly in sets of 6 or 10 colors; hexagon shape; coating color - according to the color of the rod.

Drawing pencils - for graphic works; several types were produced, differing from school ones in length and in the number of flowers in sets, from 12 to 48, mostly round, except for drawing No. 1 and No. 2, which had a hexagonal shape. All sets had 6 primary colors, additional shades of these colors and usually white pencils.

All pencils produced in sets were packaged in artistically designed cardboard boxes with multi-colored labels.

Assortment of colored pencils

Copying pencils two types were produced: graphite, that is, containing graphite as a filler, and colored, the writing rod of which contained talc instead of graphite. Copying pencils were produced in three degrees of hardness: soft, medium hard and hard. Copying pencils were produced, as a rule, in a round shape.

Assortment of copying pencils

Specialty pencils - pencils with special properties of the writing rod or special purpose; produced graphite and non-ferrous. The group of special graphite pencils included "Carpenter", "Retouch" and briefcase pencils (for notebooks).

Carpenter's pencil was intended for marks on a tree when performing carpentry and joinery work. It had an oval-shaped shell and sometimes a rectangular section of the writing rod.

Pencil "Retouch"- for retouching photos, shading, applying shadows. The writing rod contained finely ground birch charcoal, as a result of which it gave a thick line of thick black color.

Four numbers were produced, differing in hardness: No. 1 - very soft, No. 2 - soft, No. 3 - medium hardness, No. 4 - hard.

Special colored pencils included "Glassographer" And "Traffic light".

Pencil "Glassographer" had a soft core, giving a fat and thick line; used for marks on glass, metal, porcelain, celluloid, for laboratory work, etc. 6 colors were produced: red, blue, green, yellow, brown and black.

Pencil "Traffic light" It was a type of colored pencils, had a longitudinally composite rod, consisting of two or three colors, which made it possible to get a line of several colors when writing with one pencil. Pencils were designated by numbers corresponding to the number of colors that the rod wrote with.

Names and main indicators of special pencils

Pencil quality

The quality of the pencils was determined by the conformity of the core, shell, finish and packaging to the requirements set by the standard. The most important indicator of the quality of pencils were: for graphite - fracture strength, hardness, intensity of the line and slip; for color - the same indicators and (color compliance with approved standards; for copiers - the same is the copying ability of the rod. All these indicators were checked with special instruments and in laboratory conditions. In practice, to determine the quality of pencils, the following requirements should be followed. The writing rod should have be glued into a wooden shell firmly and as accurately as possible in its center; the non-centricity of the rod was determined by the smallest, i.e., the thinnest part of the shell, the dimensions of which were established by the standard for pencils of the 1st and 2nd grades; the writing rod should not come out freely from the shell when sharpening a pencil or when pressing on it from the end; should be whole and uniform along its entire length, should not contain foreign impurities and inclusions that scratch the paper when writing, should not have any obvious or hidden cracks, should not should have crumbled during sharpening and writing.When sharpening a pencil, with vertical pressure on the sharpened tip of the rod, the latter should not give chips, i.e., arbitrary breaking off or chipping of the particles of the rod. The cross-sectional area of ​​the rod at the ends of the pencil had to be even, smooth, without damage and chips. For colored rods, a line of the same color and intensity was required when writing along the entire length of the rod.

The shell of the pencils was made of good quality wood, without knots, cracks and other defects; should have low cutting resistance, i.e., it should be easily and softly repaired with a sharply sharpened knife, not break during sharpening and have a smooth cut surface. The ends of the pencils had to be cut evenly, smoothly and strictly perpendicular to the axis of the pencil. The pencil should be straight and even along its entire length, without deformation. The surface had to be smooth, shiny, without scratches, dents, cracks and varnish runs. The varnish coating should not crack, crumble and stick when wet.

By defects appearance pencils were divided into two grades: 1st and 2nd; moreover, the writing properties for pencils of both varieties should have been the same. The 2nd grade included pencils in which the deflection along the length was not more than 0.8 mm, the chipping of wood or varnish film from the end of the pencil was not more than 1.5 mm, the chipping of the rod at the ends was not more than half the cross-sectional area of ​​the rod - to a depth not more than 1.0 mm, the non-centricity of the rod is not more than 0.33 D—d (D is the diameter of the pencil shell along the inscribed circle, d is the diameter of the rod in mm), as well as scratches, dents, roughness and sagging (width and depth not more than 0.4 mm) no more than 3 over the entire surface of the pencil, with a total length of up to 6 mm and a width of up to 2 mm.

Pencils were marked with bronze or aluminum foil on one or more faces. The marking had to contain the name of the manufacturer, the name of the pencils, the degree of hardness (usually in letters) and the year of issue (usually the last two digits of the corresponding year (for example, “55” means the release of 1955). On copying pencils, the marking contained the abbreviated word “Copy” On pencils of the 2nd grade, in addition, there should have been the designation “2 s.” The marking had to stick firmly to the surface of the pencil, be clear, legible, all lines and signs should be solid and not merge.

Pencils: Ruslan, Rogdai, Ratmir (factory named after Krasin)

Pencils were packed in cardboard boxes, mainly in 50 and 100 pieces of the same name and grade. Colored pencils for school and drawing were packed in sets different colors 6, 12, 18, 24, 36 and 48 colors in one set. Graphite drawing pencils, colored drawing pencils and some other types of pencils were also produced in sets of different contents. Boxes with pencils of 50 and 100 pieces and sets of all kinds were issued with a multi-color art label sticker. Boxes with sets and pencils of 10 and 25 pieces were placed in cardboard cases or packed in packs of thick wrapping paper and tied with twine or braid. Boxes with pencils of 50 and 100 pieces were tied with twine or braid or pasted over with a paper parcel. Boxes with sets of colored pencils were pasted over with multi-color labels, usually with art reproductions.

Pencils "Cosmetics" (Slavic State Pencil Factory MMP Ukrainian SSR)

Graphite pencils "Painting", "Youth", "Colored"

Set of colored pencils "Youth" - art. 139 out of 6 pencils. The price is 77 kopecks.

Set of colored pencils "Color" - art. 127 and 128 from 6 and 12 pencils. The price of one pencil is 8 kopecks and 17 kopecks, respectively.

Set of colored pencils "Painting" - art. 135 out of 18 pencils. The price is 80 kopecks.

Colored graphite pencils "Painting", "Art"

Set of colored pencils "Painting" - art. 133 out of 6 pencils. The price is 23 kopecks.

Set of colored pencils "Art" - art. 113 out of 18 pencils. The price is 69 kopecks.

Set of colored pencils "Art" - art. 116 out of 24 pencils. The price is 1 ruble 20 kopecks.

In the section on the question Who understands the marking of pencils - 2B, B, HB, given by the author Alexander Chumakov the best answer is
Pencils differ in the hardness of the lead, which is usually indicated on the pencil and indicated by the corresponding letters. Pencil hardness markings vary from country to country. On the pencil, you can see the letters T, MT and M. If the pencil is made abroad, then the letters will be H, HB, B, respectively. Before the letters, a number is indicated, which is an indicator of the degree of hardness of the pencil.
Pencil hardness markings:
US: #1, #2, #2½, #3, #4.
Europe: B, HB, F, H, 2H.
Russia: M, TM, T, 2T.
Hardest: 7H,8H,9H.
Hard: 2H,3H,4H,5H,6H.
Medium: H,F,HB,B.
Soft: 2B,3B,4B,5B,6B.
Softest: 7B,8B,9B.

Answer from Alexander Kobzev[guru]
artists))) and draftsmen))

Answer from Sedoy[guru]
H - hard, M or B - soft and softness levels

Answer from Tiger[guru]
Pencils differ in the hardness of the lead, which is usually indicated on the pencil and is indicated by the letters M (or B) - soft and T (or H) - hard. A standard (hard-soft) pencil, in addition to combinations of TM and HB, is denoted by the letter F.

Answer from Galchenok ......[active]
2B - hard lead. B - medium hardness. HB - soft

Answer from Sergey[newbie]
B means soft lead, 2B is a very soft pencil and is good for shading, B is a soft lead pencil, H is a hard lead pencil, and HB is a hard-soft pencil. Depending on the softness or hardness, lines of different thicknesses are drawn. Well, in my opinion, NV is suitable for all cases. Well, randomly in drawing they use pencils of different softness.

Koh-i-Noor Hardtmuth on Wikipedia
See the wikipedia article for Koh-i-Noor Hardtmuth