Pencil "BLACK DIAMOND" with "swinging diamonds"

Beautiful and functional pen that writes very good with a quality ballpoint filling, and on the other side provided with a touchscreen / stylus side which is suitable for a touch screen, tablet or phone. (IPhone, Android etc.)

Crystal is a material which consists of glass containing a certain amount of lead (II) oxide. Clear lead crystal glass was in 1676 for the first time on an industrial scale produced by the English glassmaker George Ravenscroft. In scientific sense is not crystal glass crystal, because the molecules are not arranged in a regular structure. Glass consists of a mixture of silica (main component of quartz sand), and metal oxides. By heating it, melting it into a thick substance that is easy to form (blow) and hardens by cooling, in which no crystal structure is created: glass does not crystallize, but forms an amorphous solid. According to an EU directive from 1969 crystal glass is a general description of glass containing metal oxide, but within that description include multiple categories. Only the more luxurious variants must contain lead: 24 percent to 30 percent lead crystal and for volloodkristal. For the lower classes of crystalline glass and sonorous glass is 10 percent metal enough. It also need not lead, zinc oxide, barium oxide or potassium oxide is also good. If it contains more than 30 percent lead, the high lead crystal like Swarovski (approximately 32 percent lead). The higher the lead content, the higher the refractive index. A material with a high refractive index shows more sheen and has a richer color gamut. Glass with a high lead content is also used in the nuclear industry, because the lead X-rays and gamma rays better retention than normal glass.