The luster of Hetian jade belongs to oily luster, which is related to the refractive index, absorption coefficient and reflectivity of minerals. The greater the reflectivity, the stronger the luster of Hetian jade.
Under normal circumstances, light will be reflected and refracted when it hits the jade surface. Because Hetian jade is an aggregate composed of many tiny mineral particles, the gaps between mineral particles and the different particle sizes cause optical effects such as diffuse reflection and scattering of light entering jade, which makes the light reflected back to human eyes softer than the incident light.
The soft reflected light and the jade quality of Hetian jade itself form a special luster: oily luster is weaker than glass luster and stronger than wax luster, that is, the visual "greasy feeling".
When hetian jade looks at it, wipe it with a napkin to make sure it is not greasy before you can look carefully; Generally, Hetian jade rotates under natural light. If you carefully observe the jade surface, you can see whether it is strong oily luster or general oily luster, and whether it is glass luster can also be distinguished.
The so-called "powder" of Hetian jade refers to the degree of coagulation of Hetian jade. Hetian jade is generally blue in different degrees, while suet jade is yellow and pink. Like the suet white jade in Hetian jade, it looks like pieces of suet with high density and pure color. Sheep fat jade shows not only white, but also powder, which is only white and cannot be called sheep fat jade. Qinghai and Russia are not as good as Shennongjia, and the pulverization degree of seed material is higher than that of mountain material or landscape material. There are many manifestations of fat powder, such as frozen fat, coagulated fat, such as fish jelly and litchi meat, as well as milk, cheese and cream, which are often manifestations of powdery fat.
One of the characteristics of Hetian jade is oiliness. Some look dry, and oil will come out after playing for a long time, while others look oily and dry after playing for a long time. The first thing that determines oiliness is the structure of the material. Many good materials do not necessarily use skin and pores to prove his identity. Just like a mass of flour, the mountain material is flour with a glass of water for half an hour, and the landscape is flour with a glass of water for two hours, so the seed material is flour with a glass of water for six hours. This material looks moist and soft, and its density is definitely higher than that of running water and mountain materials.
If you are worried about artificial oil fraud, it is recommended to identify it!
The oiliness of hand feeling includes two aspects, one is the visual oiliness and luster, and the other is the oily feeling of hand feeling. The above is about visual oiliness, and good materials must also have an oily feeling. The oiliness of the hand refers to the oily feeling with a little resistance, just like holding a weight of oil in your hand and pushing it with your hand, there is a feeling that the oil will melt. When I first started, it was as smooth as satin in summer, and as smooth as soap when I washed my hands.
With the accumulation of playing time, oil gradually forms patina on the surface of jade, and the feeling of "oil" becomes more and more obvious. This is also the reason why Hetian jade is oily.