The terminology of the top ten jewelry appraisals
The scientific and technological appraisal of jewellery and jade is generally carried out by the jewellery and jade quality supervision and inspection agency. Collectors and ancient jade identification experts and experts can only understand the terms and qualifications in the “National Standards for Jewelry and Jade Identification†in order to understand the certificates issued by the quality supervision agencies and use accurate test results to make antique works. Correct identification conclusions. This article introduces the common terms in the "standards" and the most common jewels and jade identification certificates for the reference of jewelry and jade collectors.
1. Color:
Various colors on the surface of jewellery and jade.
2. Photographic characteristics:
Refers to the various phenomena produced by the material acting on the direction and direction of the incident light. It includes the homogeneity, heterogeneity of the material, the axiality of the heterogeneous body and the positive and negative optical properties.
3. Refractive index, birefringence:
The ratio of the velocity of light in air (or vacuum) to the velocity of propagation in jewels and jade materials is the refractive index, also known as the refractive index. The maximum difference between two or three principal refractive indices in a heterogeneous body is birefringence, also called heavy refractive index (or birefringence). The refractive index of air is N = 1 (refractive index is represented by N).
4. Absorption spectrum:
When the light of a continuous spectrum is irradiated with jewels and jade materials, the spectrum generated by absorption is selected.
5. Transparency:
Refers to the degree of light transmission of jewels and jade materials, which can be transparent, translucent, translucent, micro-transparent and opaque.
6. Gloss:
The ability and characteristics of the surface of the material to reflect light. According to the strength of the gloss, it is divided into metallic luster, semi-metallic luster, diamond luster, glass luster and the like. The special luster caused by the aggregate or surface features is grease luster, pearl luster, silk luster and the like.
7. Quality measurement unit:
According to the jewellery and jade category, the following units of measurement are generally used, namely, carat, gram, kilogram, and the like. For example, the unit of measurement for diamonds is carat (or cents), 1 gram (G) = 5 carats (CT), and 1 carat (CI) = 0.2 g (G) = 200 mg (MG). The smaller unit is the minute, 1 carat (CT) = 100 points. The pearl is measured by the grain (the diameter of the ball is larger) and the pearl grain (1 carat = 4 pearls). Another example is high-grade Hetian jade, the finished product is in grams, and the raw materials are in kilograms.
8. Density:
Density refers to the mass of material per unit volume. The unit is grams per cubic centimeter (g/cm3).
9. Hardness:
Hardness refers to the ability of jewels to resist mechanical effects such as external scoring, pressing or grinding. Hardness is usually expressed in terms of Mohs hardness. The relative hardness of minerals can be divided into 10 grades: 1 talc, 2 gypsum, 3 calcite, 4 fluorite, 5 apatite, 6 feldspar, 7 quartz, 8 topaz, 9 corundum. , 10 diamonds. The hardness test is generally not used as a routine identification item due to the micro-damaged object.
10. Internal and external features:
The external features refer to the external features of natural jewels and the external features of the cut-out jewelry. The former refers to the special phenomenon related to the crystal structure, and the latter refers to the phenomenon left during the cutting and polishing process. Internal features refer to the characteristics of the jewels and jade that remain in the growth process and are related to the growth environment and crystal structure. Internal features are essential and are an important basis for identifying natural and artificial gemstones.
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