To understand the gia certificate, we must first understand what the GIA certificate is. GIA is the abbreviation of American Gemological Institute. It was founded by Robert shipley in 193 1 year, and has a history of more than 70 years. GIA is a non-profit organization. The funds are donated by people in the jewelry industry. Since GIA does not involve profit-making business, it will not be affected by human factors on the premise of credibility first, so it has great credibility in the content quality of the appraisal book. In other words, GIA certificate, like the ID card of a diamond, records its identity information and becomes a reliable basis for us to choose a diamond.

First, the title part of the certificate

1, Gemo School of Logic USA: GIA Lab LOGO

2.9. 27. 20 14: date of issuance. This date also represents the test level and dollar price at that time. But now we are all settled in US dollars on the purchase date, so we will not pursue this date.

Second, the first part of the certificate content

1, GIA report number: diamond code, as proof of identifying GIA diamonds;

2, shape and cutting style: diamond cutting. Round is a round diamond, and diamonds of other shapes have their own unique names, such as emerald cutting;

3. Size: diamond size. 4. 19-4.2 1 x 2.67 mm, and the diameter (minimum-maximum) * height diameter is allowed in the range of millimeters.

Three. Contents of Part II -4C of Certificate

1, carat weight: diamond weight. 030 Carat. Carat is the unit of diamond weight, which is called "Carat" in Chinese. 1 g =5 carats, 1 carat = 100 integral. GIA is calculated to two decimal places, and the third place is one ninth, for example, 32.89 is 32 points and 32.9 is 33 points;

2, color grade: diamond color. I am the color of this diamond. Gem-grade white diamonds start from D color to Z color. In addition, the color of pink and other things is called colored diamond, such as fancy pink, and there are many grades in colored diamond;

3. Clarity grade: diamond clarity. VS2 is the cleanliness of the drill bit. That is 10 times the diamond content under the magnifying glass. GIA classifies diamond clarity into FL, IF, VVS 1-VVS2, VS 1-VS2, SI 1-SI2-SI3, I 1-I2-I3 and so on. , decreasing from front to back. Generally, we think that VS 1 is the one with high cost performance.

4. Cutting grade: diamond cutting. This is a new comprehensive evaluation. Look at the 4C cut and look at this! In fact, it is a comprehensive measure of many indicators, including symmetry and polishing. A good roughneck.

Four. Certificate Content Part III-Additional Information

1, polishing: polishing. Polishing will increase the brightness of diamonds. But some diamonds have natural features, such as original crystal faces, which cannot be polished off. So if this is a natural situation, don't be too demanding on polishing;

2. Carat weight: diamond weight. 030 Carat. Carat is the unit of diamond weight, which is called "Carat" in Chinese. 1 g =5 carats, 1 carat = 100 minutes. GIA is calculated to two decimal places, and the third place is one ninth, for example, 32.89 is 32 points and 32.9 is 33 points;

3. Symmetry: Symmetry. Symmetry refers to whether diamonds are cut symmetrically from left to right, because all diamonds have maximum and minimum diameters, so no diamond is completely symmetrical. If the symmetry is above good, the effect of eight hearts and eight arrows may appear, but it does not mean that eight hearts and eight arrows are easy to cut. Remember that this is only a special effect.

4. fluorescence: fluorescence. It is a natural phenomenon that diamonds have fluorescence. Blue fluorescence can enhance the brightness and whiteness of diamonds, while yellow fluorescence can be reduced. Therefore, fluorescent diamonds also depend on what kind of light. It doesn't hurt to have fluorescence, which may make the diamond more beautiful.

5. Clarity characteristics: including. Some internal features of natural diamonds, such as small crystals and cloud-like inclusions, can only be clouded under a microscope to prove the naturalness of diamonds.

6. Inscription: refers to the laser marking number of the diamond waist. GIA 1 189302345 The figures engraved on the waist of the diamond are black, and the words GIA are hollow letters, and the figures are the same as those in the report, which is the proof of identifying GIA diamonds;

Verb (abbreviation of verb) The content of the fourth part of the certificate-cut to the work mark diagram

For the information on the right side of the certificate, ordinary consumers only need to look at the cutting grade evaluated by GIA. In fact, these complex data GIA have summarized them into a comprehensive cutting evaluation.

1, full depth ratio: the percentage of the height of the diamond to the average diameter of the waist. This ratio depends on the cutting. GIA's standard is 56.8-62.4% as good-excellent;

2. Table width ratio: the percentage of table width relative to the average diameter. The size of the table is related to the size of the diamond and whether it will leak light, which is very important. GIA's standard is 52.5%-58.4% excellent. Americans prefer a small desktop, which will make diamonds full of fire. So some people say that the bigger you buy, the bigger it looks, and it looks really big, but if there are fewer diamonds, there will be no fire, and no matter how big it is;

3, diamond waist thickness: too thin waist, easy to damage the edge collapse, too thick waist will increase weight;

4. bottom tip: no. Generally speaking, the bottom tip of small diamonds is reserved, and some big diamonds will wear off the bottom tip in advance to protect the bottom tip from being damaged, thus increasing face; Except for the diamond color and clarity grading table, bar codes and squares are forged.