A solid amorphous glass mixture cooled by electrofusion. Generally brittle and transparent, the chemical composition is complex, and the main component is silicate.

Ordinary glass is made of soda ash, limestone, timely and feldspar as main raw materials, which are melted, clarified and homogenized in a glass kiln, then processed and shaped, and then annealed to obtain glass products. The main component of ordinary glass is roughly CaO∶Na2O∶6SiO2, which is a mixture of sodium phosphate, calcium silicate and silicon dioxide. Without a certain melting point, it softens in a certain temperature range and can be made into products of any shape after softening. In addition to ordinary glass, there are special glasses mainly made of borate, phosphate and fluoride.

If opacifying agents such as fluorite and calcium phosphate are added to the raw materials, opaque opaque glass can be made. For example, coloring agents such as cobalt oxide and nickel oxide are added to raw materials to make colored glass.

Tempered glass (quenched glass) can be made by heating ordinary glass to a soft temperature and then cooling it quickly and evenly. Its mechanical strength is 4 ~ 6 times higher than that of ordinary glass, and it is not fragile, so it becomes slag when broken, which is a kind of safety glass.

Glass is an important building material, which is also used for lighting and daily necessities.

Diamonds are the product of natural geological processes. It is rare, beautiful, durable and non-renewable. Because it involves a lot of professionalism and content, it is only a conceptual brief introduction.

1, composition of diamond

Diamond is a simple crystal composed of carbon (C) formed under the conditions of high temperature and high pressure in the deep part of the earth.

The unit of measurement is one carat.

Carat is the unit of weight of precious stones. "Kela" comes from a seed called "carob" in Africa. The weight of this carob seed is surprisingly consistent, and the weight of early diamonds was weighed by this seed. 1 carat equals 0. 2 grams, 1 carat cent 100 cent, that is, half a carat of diamond equals 50 cents. When the other three elements are the same, the bigger the diamond, the higher its value. Diamonds are sold at different prices according to their weight.

3.4C diamond

At present, the international standard for measuring the value of diamonds is 4C, which consists of four English letters beginning with C.

Weight carat weight-the bigger the single grain, the higher the value.

Color Color-The closer to a colorless or high-purity color, the higher the diamond value.

Diamonds can have many colors, but colorless-light yellow series diamonds are definitely the majority. At present, there is no international standard for evaluating the color of colored diamond. The standard introduced here is also aimed at colorless-light yellow-white diamonds.

There are some differences among different diamond color grading systems in the world, but they all gradually agree with the grading standard put forward by GIA. GIA and international color scales are expressed in English letters, from the highest color scale D to the lowest color scale Z, and from white to yellow. * * * has 23 scales, but our national standard divides it into 12 scales considering practicality.

In the absence of instruments, how to identify the authenticity of diamonds? Many simple and practical methods:

Identifying the authenticity of diamonds by touching them is a method often used by those who are more experienced. Touching the crystal face of a diamond gently with your fingers will make you feel sticky. This is because diamonds have affinity for oil, and people's finger skin will secrete some trace hand oil. This skin oil touches the crystal face of the diamond, which will give you a sticky feeling because of the affinity of the diamond to the oil. However, if the appraiser is inexperienced, it is still difficult to distinguish between genuine and fake diamonds, so some methods should be used with caution.

It is a relatively simple method invented by an expert in the former Soviet Union to identify the authenticity of diamonds with a pencil. When identifying, the diamond should be wetted with water first, and then lightly scratched with a pencil. On the crystal face of a real diamond, where the pencil crossed, there was no trace. If it is not diamond, but glass, crystal and other materials, it will leave traces on the surface. This simple method is very popular with ordinary diamond lovers. Another way: Take a piece of white paper, draw a straight line and clean the gem. The desktop is placed in a straight line. If it is a diamond, a straight line will not be observed through the gem, but through most diamond substitutes, a straight line or part of a straight line can be observed. This method can only be used for round drills without inlays.