Buy diamonds from the following four aspects to consider (4C):
(1) color: colorless is the best, and the darker the tone, the worse the quality. In the color classification of colorless diamonds, the top color is D, arranged in the order of Z, and only the color grades from D to J are mentioned here. D-F is colorless, and G-J is almost colorless. There is basically no collection significance from k down, but the ring holder below k color will look good if it is made of gold. Because diamonds will gradually turn yellow from K, when we choose diamonds, we should try to choose the color above H. Although I-J belongs to the category of near colorless, we can still detect a trace of yellowish. Colored diamond, such as red, pink, green and blue, is a treasure in diamonds, and its price is expensive. Among them, red diamonds are the most precious.
(2) Clarity: Clarity classification is based on the location, size and quantity of inclusions. The clarity grades are divided into FL, IF, VVS 1, VVS 2, VS 1, VS 2, SI 1, SI2, SI3 and P65438 from high to low.
These include:
FL-"perfect", perfect. There are no flaws inside and outside under a magnifying glass of ten times.
If-"immanent", immanent. Under the magnifying glass of ten times, only the surface has slight flower marks.
Vvs 1, vvs2-"very very thin", very very small. Defects that are difficult to see only under a ten-fold magnifying glass. The net crossover of VVS 1 is higher than VVS2.
VS 1 and vs 2-"very thin", very small. Defects can be seen under a magnifying glass of ten times, but it is difficult for the naked eye to recognize them. The net crossing of VS 1 is higher than that of VS2.
Si 1 and si2- "slight inclusions", small flaws, which may be visible to the naked eye.
I 1, I2, i3-"Imperfect" is flawed and visible to the naked eye.
(3-carat weight): When the other three C's are the same, the price of a diamond is directly proportional to the square of the weight, and the greater the weight, the higher the value. The weight of diamonds is measured in carats. 1 carat (carat) = 0.2g (gram). Divide one carat into 100 parts, with one point for each part. The 0.3 carat and 0.4 carat marked on the price tag of the mall are what we call 30 points and 40 points. The weight will also be graded, 0.30ct-0.39ct, 0.40ct-0.49ct, 0.50ct-0.69ct, 0.70-0.89ct and 0.90. 1.00ct- 1.50ct, 1.50-2.00ct (each level is separated by a comma, not the first level, even if it is one point away, the price will vary a lot, which is why it is like 0.48~0.49, 0.68~0.69, 0.
(4) Cutting: A diamond's original stone will not be noticed even if it is thrown on the road. It is cutting that gives it a second life and gives it a gorgeous fire color. Cutting refers to the geometric shape and arrangement of various valve faces of finished bare diamonds. Cutting is divided into three categories: cutting ratio, grinding and decoration. Each project has five grades, from high to low, excellent, very good, good, average and poor. Generally, what we see is the standard round drill cutting. Top-cut stones can reflect light in the most perfect proportion, which is what we call three EX (excellent) cuts, but the price of this cut will be a little more expensive, because its yield is relatively low, which will be about 5% higher than that of stones without three EX cuts, but the fire color of three EX cuts is absolutely the most beautiful.
Several common cutting forms
Round emerald oval pear princess square pillow.
[Edit this paragraph] logo
Diamonds are appraised by internationally recognized gem experts, and independent opinions are issued by third parties. Determine the price of diamonds based on 4C standard.
At present, the most authoritative gem identification laboratories in the world are IGI and GIA.
Simple identification method of diamonds: you need a magnifying glass of 10-20 times as an aid to make a few simple observations.
Method 1: Observe the waist of the diamond, if there is a frosted waist, it is most suitable. Because diamonds are harder than any imitations, they don't have thin lines like imitations, and the waist of diamonds has a granular appearance.
Method 2: Diamond is harder than imitation, and the facet edge of imitation is often blunt than diamond, and the facet edge of diamond must be sharp.
Method 3: Based on the fact that diamonds are harder than imitations, the faceted edges of imitations often wear out.
Method 4: If a diamond has a natural surface, there is a chance to find a unique "triangular growth line" on the natural surface.
Method 5: If the diamond is broken, the appearance is usually stepped, while the imitation will be completely bent or shell-shaped.
Simple identification method
Diamond, whose mineral name is Diamond, is recognized as the king of gems. Its biggest feature is the highest hardness, strong refractive index and shining in the light. But its surface is similar to glass, crystal and artificial diamond, which is difficult to distinguish. Accurate identification only depends on instrument measurement, and simple identification can adopt the following methods:
1, hardness test
Diamond is the hardest natural substance known, and nothing can mark it. If you can mark it, it's definitely not a diamond.
2. Thermal conductivity test
At the same time, breathe into the diamonds and other similar objects to be debated. If it is a diamond, the water mist condensed on its surface should evaporate faster than other objects, because the thermal conductivity of the diamond is high.
Step 3 Observe the reflected light
With a magnifying glass, it can be observed that the waist of the diamond presents a very fine matte shape, and the reflected light shines. This characteristic of diamonds is unique.
Step 4 look at the growing point
Observing under a magnifying glass, there are often grooves and triangular growth points on the crystal face of real diamonds, but there are three kinds of fakes: ① Ordinary glass with alumina is easy to get into the wrong place, because the refractive index and dispersion increase, but the hardness is lower. (2) Imitated with chemically synthesized sapphire and colorless spinel, the hardness is similar, but the refractive index is low and has birefringence, and the double image can be seen under a magnifying glass.
5, similar chemical composition test
The chemical composition of pencils is carbon, just like diamonds, but the physical structure is different, so many people use pencils to detect the authenticity of diamonds, which is a practical and effective method. When identifying, the diamond should be wetted with water first, and then gently scratched with a pencil. On the crystal face of a real diamond, there is no trace where the pencil crosses, but if it is not a diamond, but a material such as glass and crystal, it will leave a trace on the surface. Under normal circumstances,
6. Artificial zirconia imitations have higher hardness and better refraction, but they will reflect more colored light when rotating, which is obviously different from the genuine ones that only reflect weak yellow and blue light when rotating.
certification authority
GIA Certification [4] Gemological Institute of America is the founder of promoting the internationalization of diamond certification. It was founded by Robert shipley in 193 1 year, and has a history of nearly 70 years. GIA is a non-profit organization, and its funds are donated by people in the jewelry industry. GIA is not involved in for-profit business and will not be affected by human factors under the premise of reputation first, so it has great credibility in the content quality of the appraisal.
IGI certification [2] (international gemo logic institute)
Igi (International Gemological Institute) is the world's top gemological institute and the largest independent jewelry appraisal laboratory in the world. As the oldest gem institute in the diamond capital of the world, IGI was established in Antwerp, Belgium, with the telephone number: 1975.
HRD Certified Diamond High Council -[3] (Belgian Diamond High Council), established in 1973, mainly coordinates the activities of Belgian diamond industry. Over the years, HRD in Antwerp has become an official organization recognized in Belgium and internationally, and plays the role of organizer, spokesperson and media in the diamond industry in Antwerp.
Other diamond certificates
China NJQSIC certificate China NGTC certificate China NGGC certificate
American GTC certificate American GTA certificate American EGL certificate
Japanese CGL certificate and American GEMES certificate