With the improvement of people's living standards, crystals have become more and more popular in China. Famous fashion brands such as Chanel and Dior are also decorated with Swaroski crystals. Crystals have also moved from jewelry, ornaments and displays to fashion, shoes and hats, and watches.

Some famous foreign architectural glass companies also produce crystal flat glass and crystal glass architectural products for high-end buildings. In foreign countries, the Crystal Club appeared very early, and there are a large number of crystal fans. There are also specializing in crystalHandicraft processingCounties, towns, such as Crystal City and Crystal Palace.

However, at present, according to the Chinese translation in the dictionary, the so-called crystal crystals in non-academic newspapers, websites and corporate promotional materials at home and abroad are called crystals. They are not traditional quartz crystals (quartz crystals), nor are they crystal balls processed by some crystal cities in China. The K9 optical glass used in crystal crafts is crystal glass. In quartz producing areas such as the East China Sea in Jiangsu Province, the crystal is still a traditional quartz crystal.

Crystal glass has a long history. In ancient times, due to the many impurities in the glass raw materials, the melting temperature was not high, the glass could not melt well, and there were many unmelted sand particles, bubbles and other defects. At the same time, the raw materials contain many non-ferrous metal ions, such as iron, manganese and titanium. Is opaque or translucent. In the 13th century, the Venetians used quartzite with less impurities and sodium-containing vegetable ash from the Levant to melt it into colorless and transparent glass. In the 15th century, the quality of raw materials was further improved. Using pure quartz sand and soda ash recrystallized from a boiling aqueous solution of plant ash from the lower reaches of the Ticino River, the transparency of the resulting glass is significantly higher than in the past, similar to crystals, so it was named Cristallo. A sodium-calcium crystal whose composition range (mass fraction) is [1] SiO270.0%～71.5%, Al2O30.8%～1.31%, CaO4.07%～4.72%, MgO1.47%～1.66%, K2O2 。84%~4.55%, Na2O15.2%~16.8%, Fe2O30.25%~0.51%, MnO0.26%~0.51%, SO30.19%~0.31%, Cl0.62%~0.92%, P2O50.15 % Is about 0.24%. Fe2O3 and MnO in this composition are impurities in mineral raw materials, while Cl and P2O5 are impurities in plant ash soda ash.

The composition of soda lime crystal glass is somewhat similar to modern ware glass. The content of K 2 O + Na 2 O is relatively high, while the content of CaO + MgO is relatively low. The glass is easy to melt and is suitable for manual operation. After the 13th century, the Bohemians established more than a dozen glass factories in Bohemia (now the Czech Republic) and Silesia. In addition to using high-quality quartz sand as raw materials, they also use potassium carbonate-containing tree ash (such as wood ash from beech forests) as raw materials to introduce alkaline oxides, so transparent glass with a higher refractive index, also known as crystalex , Is made for different from Venetian crystal glass in the literature, it is called Bohemia Crystalx (Bohemia Crystalex). Because it uses forest wood ash as a raw material, it is also called Forest Glass (ForextGlass). Bohemian crystal glass is made of potassium calcium, containing SiO275%~77%, CaO5%~6%, K2O15%~17%, and the refractive index of the glass is 1.48~1.49. This system is called potassium-lime crystal glass.

Later, in order to improve performance, Na2O and a small amount of B2O3 were added to the composition, and it was renamed as potassium sodium calcium salt crystal glass. The current composition (mass fraction) of this type of crystal glass produced in the Czech Republic is SiO27.55%, B2O30.2%, CaO6%, K2O4.8%, and Na2O12.8%. Potassium-calcium-potassium-sodium crystal glass is mainly produced in November. Bor, a small town 90 kilometers away from Prague. The technical indicators of the product are: density 2.444g/cm3, refractive index nD (20°C) of 1.50002, average dispersion (20°C) of 830×10-5, linear expansion coefficient of 89.1×10-7°C-1, acid resistance (According to the ISO719 standard, 0.01mol/L HCl at 98℃, the weight loss per unit area of ​​the glass surface) is 1.98 mg/dm2, and the liquidus temperature is 950℃[2].

In the Middle Ages, Bohemian crystal glass manufacturing technology gradually spread to Central and Western Europe. The glass factories in the UK and France mostly use Bohemian potassium calcium and soda lime glass components. The melting temperature is relatively high, and high-quality wood is required as fuel. A lot of forest has been cut down. In 1615, the British royal family banned the use of high-quality wood as fuel in the glass factory, which affected the production of the glass factory. In 1670, the British Ravenscroft discovered that adding PbO to the glass composition not only reduces the viscosity and melting temperature of the glass, the glass is easy to melt, the material is long, the shape is convenient, and the glass has high gloss. The glass has increased, it is more transparent and easy to grind. , Put lead glass into production, called lead crystal. The refractive index, dispersion and density of lead crystal are higher than Cristallo and Crystalex, and its melting, forming and grinding properties are better than soda-calcium and potassium-calcium crystals, so it has been widely used.