Rock crystal has admired man at all times, but the most surprising thing is that ancient civilizations learned to process this solid material using sand, i.e. materal same hardness. Rhinestone was used for the manufacture of jewelry and luxury items, for the higher layers as well as various magical attributes. This created an additional halo of grandeur of grandeur and mystery. In the end, no wonder the crystal ball is considered the most perfect predictor?
The famous bohemia crystal Czech republic has a long history - the first primitive “sklar” appeared here in Celtic times. Nevertheless, Czech glass was first mentioned in archival records only in 1162, and the first workshops of glassblowers appear in old chronicles at the end of the 13th century. They arose in the sparsely populated then mountains like Šumava or Krkonoše, where there were forests and therefore a cheap tree. Already in the Middle Ages, Czech glass was famous for its high quality and was sold in German lands (the tax archives of Frankfurt am Main mention Czech glass in 1435), France and Flanders, but its export was limited to a competitor - at that time Europe was firmly in the hands of Venice, whose masters were able to produce very clean soda, necessary for the production of glass.
Crystal products are always produced annealed - this is a specific way to temper glass. The product heats up to 700 ° C and is then quickly and evenly cooled using a blower. In this case, the strength of the product increases by 6–8 times, and the heat resistance - by 2–3 times.
In the 16th century, there were already 34 glass factories in the Czech Republic, several famous glass masters from neighboring Saxony moved here. The craft was so honorable that Emperor Rudolf II bestowed titles of nobility to two families of glass craftsmen - Schürer and Wandera. At the same time, the masters began to paint glass for the first time and at about the same time they learned how to make clean glass without impurities. In the 17th century, the quality of Czech glass became much better than Venetian, and in addition, Venice was weakened by the Thirty Years War, and so Czech products were sold throughout Europe and exported to Asia and America. The most famous and successful seller of glass of those times was Georg Kreibich from Kamenitsky Shenova, who visited almost all European states, including Russia (he visited Moscow and St. Petersburg).
At the same time - the end of the XVII - the beginning of the XVIII century, after a series of experiments, the famous Czech crystal appeared, resembling natural rock crystal. The pioneer was master Michael Muller, who, experimenting with the addition of lead, received plastic glass in 1683, which was easy to shape. None of the competitors from other countries had anything like this, the Czech “sklarna” literally did not have time to produce crystal - so great was the demand. Venice was in a desperate situation - they banned the import of glass into the republic and persuaded several craftsmen to move in with them. Of the 25 glass factories in the north of Italy, only 4 survived.
Rock crystal is used in radio engineering to obtain ultrasonic vibrations. From it make prisms of spectrographs, lenses. Painted rock crystal crystals are used as semi-precious stones. Rhinestone is used to make jewelry and luxury items, as well as various magical paraphernalia; Bohemian - lead free (potassium-calcium glass); barium - barium is added instead of lead; lead - was invented 350 years ago in London by the scientist Rovencroft. Since then, it has become widespread throughout the world. The lead oxide content is from 6% to 36%. Brewed at a temperature of about one and a half thousand degrees. The most complex physicochemical processes take place, as a result of which very stable complex compounds are formed. Crystal is not destroyed by acidic, alkaline or alcohol-containing liquids, therefore it is absolutely harmless. World standard - 24%.
The most important parameters of any kind of crystal - its composition, accuracy of cut and quality of polishing. Today, there is a tendency to avoid faceted crystal. Opaque glass is also popular. Colored crystal is obtained using special additives. Red due to the addition of cadmium or gold compounds. Silicon gives the crystal a pink hue. Blue colored crystal owes its tone to cobalt. Copper oxide and manganese oxides make the crystal green and purple. Iron is bluish-green or yellow, uranium is yellowish-green, chromium is grass green, and manganese is yellow or brown, depending on the concentration.