The evaluation of diamonds should be based on the four standards of "clarity, color, cut and weight".

1. Clarity: Diamonds are natural products with some flaws. These defects are small crystals, clouds, pinholes and small cracks wrapped in the diamond during its growth. Clarity grading is carried out by professionals under the magnifying glass of 10 times. According to the size, quantity and location of the observed defects, it is divided into five grades, namely 10.

2. Color grading: Color grading is obtained by observing the obvious degree of yellow (brown) tone in yellow series diamonds, and the classification of diamond color grading is completed by professionals in a specific environment. The color of diamonds is divided into 12 grades, and different color grades are represented by English letters.

3. Cutting classification: Through the measurement and observation under the microscope, the quality of diamond cutting and grinding process is classified, and the ratio instrument is often used for classification. The degree of modification is the symmetry of diamond cutting and grinding and the evaluation of surface polishing quality. As a consumer, we should judge the quality of cutting from the following aspects: whether the diamond is bright, whether the fire color is obvious, whether the shape is symmetrical, whether the surface is damaged and so on.

4. Quality (commonly known as weight): it is an important factor to evaluate the value of diamonds. The mass unit of diamond is gram (g), which can also be expressed by (ct), lg=5ct. In fact, most of the weighing is directly weighed with a carat scale, and the carat value is reserved to two decimal places, and the third place is eight rounds.

According to the clarity and color grade of inlaid diamonds, the quality of inlaid diamonds is divided into five grades: excellent, very good, good, good and general. The influence of diamond cutting on quality is not considered.

Two. Gem is the general name of natural jewelry, jade and artificial products. Gem is the most beautiful and precious natural mineral. Bright color, crystal texture, brilliant luster, hard and durable, rare. It is a natural mineral single crystal, which is used to make jewelry, such as diamonds, rubies, sapphires and emeralds. There are also a few natural single mineral aggregates, such as opal, and a few organic non-minerals, such as amber, pearl, coral, coal essence, ivory, etc., which are also included in the generalized gem.

Jade is also the beauty of stone. It is inferior to precious stones in texture and price. But it also has bright colors, hard and delicate texture, and shiny luster after polishing. Jade has a narrow sense and a broad sense. In a narrow sense, it only refers to jadeite (represented by Burmese jadeite) and nephrite (represented by Hetian jade). Broadly speaking, it includes many kinds of minerals and rocks used for handicraft carving. As for colored stone, it refers to the low-grade arts and crafts stone with beautiful and delicate color and texture, low hardness and weak luster, but it can meet the requirements of processing technology. Some scholars advocate that colored stones should be included in the broad sense of jade, or that colored stones should be used as synonyms for jade for the time being.

Gemstones are mostly single mineral crystals, which are transparent and faceted. Translucent to opaque ones are often processed into plain ornaments, and the back part has starlight and cat's eye effects. Diamonds, rubies, sapphires, emeralds and golden-green cat's eyes are recognized as five precious gems, which have the value of preservation and collection, and the rest belong to middle and low grade gems.

Jade is divided into white jade, jasper, sapphire, jet, topaz, topaz, green jade, Beijing white jade and so on. Geographically, there are Xinjiang jade, Henan jade, xiuyan jade jade (also known as Xinshan jade), Australian jade, dushan jade jade, Southern jade and Canadian jade, among which Xinjiang Hetian jade is a famous specialty in China.

Three. Types of precious metals and their content requirements

Precious metals of gold, silver, platinum and palladium

According to GB 1 1887-2002, precious metal jewelry currently on the market can be divided into four types: gold jewelry, silver jewelry, platinum jewelry and palladium jewelry.

gold ornament

According to the different gold content, it can usually be divided into 18K gold, pure gold and thousands of gold. 1K is equal to 100% divided by 24, that is, 1K is about 4. 1667%. The theoretical purity of 24K is 100%.

① The gold content of 18K gold jewelry is not less than 750‰, which can be identified as18k or G 18K, G750, Au750, Au 18k and Au 750.

② The gold content of pure gold jewelry is not less than 990‰, which can be identified as pure gold or G990, Au990 and Gold 990.

③ The gold content of thousands of gold jewelry is not less than 999‰, which can be identified as thousands of gold or G999, Au999 and Jin 999. In addition, some gold ornaments such as 9K (gold content not less than 375‰), 14K (gold content not less than 585‰) and 22K (gold content not less than 9 16‰) can be seen in the market (especially abroad).

Silver jewelry

Common silver ornaments on the market are

(1) 925 silver, also known as tattooed silver, requires that the silver content should not be less than 925‰, and the other 75‰ can be copper or antioxidant elements, which can be identified as S925 or Ag 925 and Ag925.

(2) Foot silver, with a silver content of not less than 990‰, can be identified as S990 or Ag 990 and Ag990. Occasionally you can see 800 silver (the silver content should not be less than 800‰). In recent years, it has been found that in order to prevent the oxidation of silver jewelry, manufacturers often plate a layer of nickel on the surface of 925 silver and foot silver, which can easily be mistaken for fake or imitation silver products if they are not careful when testing.

Platinum jewelry

Platinum is also called platinum. In recent years, with the continuous improvement of consumption level, platinum ornaments are increasingly favored by urban and rural consumers. In the jewelry market, common platinum jewelry includes Pt900, Pt950 and Pt990.

(1) Pt900, with a platinum content of not less than 900‰, can be identified as Pt900 or Pt 900.

②Pt950, which requires that the platinum content should not be less than 950‰, can be identified as Pt950 or Pt950.

(3) Pt990, which requires that the platinum content should not be less than 990‰, can be identified as Pt990 or Pt 990, which is sufficient platinum. Occasionally, you can see Pt850 (platinum content shall not be less than 850‰) and Pt750 (platinum content).

Not less than 750‰).

Palladium jewelry

Precious metal palladium was only made into jewelry this year. It was once used as a mixture in platinum jewelry and is a new member of the precious metal jewelry family. At present, the most popular palladium ornaments on the market are Pd950 and Pd990.

①Pd950, which requires that the content of palladium should not be less than 950‰, can be identified as Pd950 or Pd950.

②Pd990, which requires that the content of palladium should not be less than 990‰, can be identified as Pd990 or Pd990. Palladium jewelry with a palladium content of not less than 750‰ and 500‰ is mainly used for inlaying. It is not allowed to call palladium ornaments "palladium platinum ornaments" or "palladium platinum ornaments" and other ambiguous names. In addition, the standard also requires that the weight of precious metal jewelry should be kept to two decimal places, and the negative deviation of the weight of a single jewelry with a weight less than 100 g should not be greater than 0.0 1 g.

Four. Like diamonds

First of all, when you collect it, you can't mix it with other jewelry to avoid mutual wear and scratches. You should wrap it in a small cloth bag or plastic bag. Because diamonds are relatively lipophilic and cannot contact chemicals and sweat, it is best not to wear them when doing strenuous exercise such as housework, swimming or bathing. When cleaning, you can use hot water, mild detergent and soft brush to clean. Mainly to remove dirt, but it is best to set a date to come to our Dongxiang franchise store for free cleaning.

Maintenance knowledge of precious metal jewelry

: 1. Avoid wearing precious metal drinks for housework or heavy work.

2. Avoid contact with metals such as mercury and lead.

3. Avoid contact with chemicals.

4, the sweat of the human body will erode precious metal jewelry, and it is best to wash it with water every day.

5. Avoid wearing it when taking a shower or sleeping, and don't pull, pull or fold it.

Five. Emerald a, b and c goods

A batch of jadeite jade without any chemical treatment

The optimized jadeite also belongs to Class A and does not need to be proved in the certificate. The main optimization methods are:

Bleaching: It refers to soaking jadeite in dilute acid to "clean" the impurities on the surface of jadeite. The structural damage is only on the surface, and there is no filler (except waxing during polishing).

Wax invasion treatment: increase transparency, improve appearance and play a role in filling surface cracks.

Class b goods

Strong acid bleaching has seriously damaged the structure of jadeite, and a large number of polymers must be injected for reinforcement before it can be used. The certificate must indicate "treatment".

C goods

The primary color of jadeite is poor, and the bright color produced by dyeing treatment should also be marked "treatment".

Simple identification of jadeite B and C goods

Put the jade under the fluorescent lamp and observe its color change. Goods A and C are unchanged, and goods B are fluorescent white. C goods are dyed, so their colors are uneven along the cracks, which can be seen with the naked eye.

Because of the limitation of words here, let's say so much. I hope it can be useful to the landlord.