First, shape and grinding (shape &; The shape of a diamond refers to its correct contour, that is, the shape of the waistline, such as circle, olive, square and so on.
Diamond cutting is the first C of diamond 4C. Due to the different shapes, numbers and arrangements of facets, diamond cutting has various forms, such as brilliant, stepped, mixed, etc. There are many kinds of cutting and grinding forms of diamonds, but the most common form is full-cut BRILLIANT, usually called BRILLIANT, which has 58 facets, that is, 33 facets at the crown and 25 facets at the bottom (including pointed bottom, or 24 facets at the bottom if there are no facets), and the most common shape is round, that is, round brilliant.
All other shapes or forms of cutting and grinding except round and bright are collectively called fancy cutting. Fancy cutting and grinding is just a general term, which can be divided into the following three categories if further classified: first, round bright varieties: olive bright, pear bright, oval bright, heart-shaped bright and so on; Secondly, it is a square cut by emeralds: it includes all kinds of square diamond shapes, such as horse's head, fish, butterfly, tennis racket, cross, triangle, half moon, portrait of human head, and so on.
The other two nouns are also common in the column of shape grinding: 1. Combined or mixed cutting: the top is one form and the bottom is another. 2. Modified cutting: slightly modified cutting according to a certain type. The so-called brilliant cutting is that the facets are arranged radially, just like the light of the sun, the moon and the stars radiates outward. For example, the crown is bright, the center is the desktop, and there are usually eight kite faces, eight star faces and sixteen waist faces around it. The bottom is usually centered on the bottom tip, and the facets radiate outward like light.
The so-called step cutting, that is, emerald cutting, means that facets are arranged in layers, one by one from the center to the outside. Hybrid cutting mill is a stepped cutting mill combined with bright cutting mill.
The narrative method of modeling and cutting and grinding is to write modeling first, then cutting and grinding style. E.g., a round diamond is correctly described as a round brilliant cut); If the top and bottom are bright; The same diamond, if the crown is bright and the bottom is stepped, is written as a circular mixed cut.
Second, the size (measurement method) The size of the diamond is in millimeters (or abbreviated as mm, usually abbreviated), and recorded to the second decimal place below millimeters. Because the position of each measurement may not be exactly the same, there will be slight errors when using different gem measuring calipers. If there are two different certificates for the same diamond, the size will be slightly different, and the results of the second measurement before and after will be different, but the limit will not exceed 0.02 mm
Under the precise measurement of decimeter calipers, round diamonds are not pure circles, so the minimum and maximum diameters and the total depth are recorded, while colored diamond records its length, width and height, so there are three size figures. 3. Weight is measured in metric carats, which is the second C of 4C diamonds, and each carat is equal to 200mg.
Or 0.2 grams, so 1 gram equals 5 carats. The weight of a diamond is accurate to the second decimal place below carat, and the third decimal place can be rounded off or omitted according to the situation.
The second place after the decimal point is "point", and each carat is equal to 100 point. In the Middle East, there is a kind of Sophora japonica whose seeds are the same weight and size.
The English name of this tree is CAROB TREE, which is quite common in the local area. In ancient times, pearl merchants first used their own seeds as the weight unit of pearls, that is, carats, that is, carats as the source of weight units.
Carat has been widely used as a unit of weight for precious stones. At first, the carat weight in different areas was slightly different. However, since 19 13, the United States has stipulated that each carat is equal to 200 mg, and all advanced countries take this as the standard, so there is no competition. 4. The cutting and grinding ratio (proportion) of full depth percentage (depth%) diamond mainly includes the following items: waist width (average width of round diamond) is 1, or 100% is taken as the benchmark: (1) full depth percentage (depth%), (2) table%. (3) perimeter thickness, (4) base size and surface modification, (5) polishing or polishing, and (6) symmetry.
The percentage of the full depth of a round diamond is a number obtained by dividing the full depth (thickness) by the average of the minimum diameter and the maximum diameter, and then converting it into a percentage, in other words, it is the percentage of the thickness and diameter of the diamond. The percentage of full depth is calculated to the first decimal place, and the second decimal place is rounded off.
For example: round drill: diameter 6.50-6.59, thickness 3.83→ (6.50+6.59)/2=6.545=6.55 (rounded corner), 8.83/6.55=0.5847=58.5%= full depth percentage. Colored diamond is obtained by dividing the height (full depth) by the width, regardless of the length.
For example, colored diamond: length 13. 18, width 8.24, height 5.45 → 5.45/8.24 = 0.6614 = 66.1%= full depth percentage. The main purpose of recording the percentage of full depth is only to know the approximate thickness of the diamond. The greater the percentage, the thicker the diamond and the smaller the diamond.
However, the total depth of a diamond is deeply influenced by the surface size, crown height, waist thickness and bottom depth, especially the surface size changes the most. When the table is large, the crown is thin, resulting in a small percentage of the total depth and a large percentage of the total depth. The ideal crown angle should be 341/2 and the base depth should be 43. 1%.
However, according to the actual observation experience, if the crown angle is in the range of 32 ~ 36, the bottom depth is between 42.5% and 45. . .
How to see the fineness of diamonds and how many grades are there? What's the difference between the best and the worst? -Search
The quality of a diamond depends on its 4C (color, purity, cut and carat weight) classification:
Color classification: d, e, f, g, h, I, j, k, l, m and n clarity classification: China: LC, VVS 1-2, VS 1-2, SI 1-2 and p/kloc-2.
GIA:FL-IF、VVS 1-2、VS 1-2、SI 1-3、I 1-3。
Cutting classification: five grades: excellent, good, medium and poor.
Cutting classification is to classify diamond processing technology from two aspects: proportion and degree of modification. The modification degree includes polishing quality and symmetry deviation. The ratio is classified as: very good, good and average; Polishing and symmetrical classification refer to cutting classification.
In addition, the fluorescence reaction is also graded, and the standards are: none, weak, medium, strong and very strong.
Weight classification: based on the direct weighing of bare diamonds, the weight units are carat (ct) and minute (pt), 1 carat = 100 minute = 0.2g The higher the carat weight, the more expensive the diamond with the same quality.
The best indicators rank first, and the quality decreases step by step. Color: m, cleanliness: below I3, rarely seen in the market.
For reference only.
What is the fineness of diamonds? what do you think? What kind of diamond is good?
How to look at one of the diamond appraisal certificates, GIA certificate, the value of diamonds depends on the four C words of diamonds. Some people call the diamond appraisal certificate the fifth C word of diamond.
In fact, according to the name marked by the American Gemological Institute, it is "diamond classification report" or other unrealistic names. Today, the diamond classification system and terminology established by Gemological Institute of the United States have long been recognized by the public as the international diamond language, and many appraisers who use other systems also cite its terminology.
There are many practitioners in cash gem appraisal offices. Although not all of them graduated from Gemological Institute of the United States, the diamond appraisal standard used is still based on the system established by GTL, because no other system can replace extensive public recognition. GIA, the origin of diamond certificate, was established in Los Angeles 19 13. At first, it trained jewelers how to evaluate prices through evening classes and correspondence courses, and provided reference materials for wholesale prices of jewelry.
But before evaluating the price, we must first determine the quality. In order to meet the needs of facts, GIA has established its own system to evaluate the quality of diamonds and other precious stones.
After World War II, new york's position in the diamond market became more and more important. More and more jewelers asked GIA how to determine the quality of diamonds, so that after 1953, GIA set up its first appraisal office in new york and began to issue diamond certificate reports, commonly known as appraisal certificates, to meet the demand.
In addition to the inspection office in new york, two other inspection offices have been established in Santa Monica, California and downtown Los Angeles (now the Los Angeles inspection office has been built), so there are mainly two inspection offices. The official name of these appraisal institutions is "GEM TRADE LABORATOR, Inc.", which belongs to GIA and only appraises gems, but does not.
GIA is a non-profit organization established with the support of famous American jewelers and celebrities. Therefore, GIA is an appraisal research institution enjoyed by American jewelers, and its subsidiaries, such as GTL, provide appraisal services for jewelers, which is widely trusted by all walks of life and is not discriminated against because of the support of American jewelers.
The appearance of diamond identification certificate has greatly changed the diamond trading. In the past, it was necessary to identify the quality one by one, but now you can refer to the identification certificate. According to GTL's statement, GTL is not responsible for the certificate issued by GTL if it is used as the basis for trading.
However, because its certificate is widely welcomed and trusted, many jewelers are happy to use it as the basis of diamond quality. The circulation of certificates was originally only between diamond dealers and finally reached consumers. It is popular not only in America, but also all over the world. Therefore, the demand for certificates is increasing, and the demand exceeds the supply, which has formed the bottleneck of diamond trading.
The role and effectiveness of diamond appraisal certificate The real significance of diamond grading report is diamond quality grading report. GIA has repeatedly stated that it is a report, not a certificate. The main purpose of this kind of report is to distinguish the true from the false: anyone with a diamond identification certificate is obviously a diamond, not another kind of gem or diamond counterfeit.
? Characteristic record: The weight, size and fluorescence reaction recorded in the appraisal book are all characteristics of identifying diamonds. In particular, the characteristic inclusions of diamonds drawn in the attached drawings are a clear identification mark. If you don't draw the surface features or inclusions of the diamond and explain the diamond identification certificate, this function will be gone.
? Quality analysis: the weight, color, clarity, grinding (commonly known as lathe worker) and proportion of diamonds are all stipulated in the appraisal certificate, so the appraisal certificate is the analysis record of diamond quality. ? Valuation reference: before a diamond is valued correctly, it is necessary to know its quality first.
Most of the information about quality in the appraisal certificate is explained, so the appraisal certificate is an important reference document for the value of ancient diamonds. ? Retained materials: All the materials recorded in the certificate are very clear reference materials for future re-evaluation, procurement cost analysis and sales statistics.
First, shape and grinding (shape &; The shape of a diamond refers to its correct contour, that is, the shape of the waistline, such as circle, olive, square and so on. Diamond cutting is the first C of diamond 4C. Due to the different shapes, numbers and arrangements of facets, diamond cutting has various forms, such as brilliant, stepped, mixed, etc.
There are many kinds of cutting and grinding forms of diamonds, but the most common form is full-cut BRILLIANT, usually called BRILLIANT, which has 58 facets, that is, 33 facets at the crown and 25 facets at the bottom (including pointed bottom, or 24 facets at the bottom if there are no facets), and the most common shape is round, that is, round brilliant. All other shapes or forms of cutting and grinding except round and bright are collectively called fancy cutting.
Fancy cutting and grinding is just a general term, which can be divided into the following three categories if further classified: first, round bright varieties: olive bright, pear bright, oval bright, heart-shaped bright and so on; Secondly, it is a square cut by emeralds: it includes all kinds of square diamond shapes, such as horse's head, fish, butterfly, tennis racket, cross, triangle, half moon, portrait of human head, and so on. The other two nouns are also common in the column of shape grinding: 1. Combined or mixed cutting: the top is one form and the bottom is another. 2. Modified cutting: slightly modified cutting according to a certain type.
The so-called brilliant cutting is that the facets are arranged radially, just like the light of the sun, the moon and the stars radiates outward. For example, if the crown is bright, the center is a table.
Diamond fineness
Personally, I don't think it's worthwhile. First of all, diamonds depend on their size. Of course, the bigger the better. D is quite white and bright, and there is nothing wrong with VVS 1 or 2, but 32 cents is too little. 18800 yuan can buy 50-60 cents of diamonds, and the quality is quite good. Let's talk about color first. D is very white and very bright, while E is very bright. Let's talk about clarity first: clarity refers to the defects presented under the magnifying glass of 10 times, which are absolutely invisible to the naked eye and have no influence on the brightness and fire color of diamonds! So you can also choose VS or SI. It is impossible for others to see the defects of diamonds with a magnifying glass. Hehe ... Then say something else. I chose this kind of diamond for your reference. Hehe ~ there is a price range. With this range, you have to choose the largest diamond in this range! Diamonds must be very big. Diamonds below 1 carat have no hedging function. Of course you brought it yourself ~ so choose a big one! Then look at the 3EX of the diamond. Personally, I think I need 3EX. If a diamond is good in color and flawless, but not well cut, it will not show the beautiful fire color of the diamond! After reading these, I'm looking at the colors. The landlord likes white diamonds and bright diamonds, and chooses D\E\F\H color. The most affordable choice is H color (popular), and finally look at the clarity ~ In addition, diamonds had better have certificates, not to mention domestic certificates. GIA (personal) is the best. I don't know if I understand this, I hope.
What grade of diamond is the best?
The purity of the diamond is 1. The fineness refers to the degree of a diamond's lack of fineness, and the whiteness of a diamond is graded.
2. The color grade D is the highest grade and Z is the lowest grade. The color of the diamond itself is light yellow.
This is exactly the grading of diamond fineness according to the degree of insufficient fineness. The lighter the color of the diamond, the higher the fineness grade.
After cutting, color is usually considered as the second important feature in selecting diamonds. This is because human eyes tend to perceive the brightness (refraction) of diamonds first, and then the color.
The colors of diamonds are divided into two series. Common colorless series include colorless transparent, nearly colorless and light yellow. There are also color series including dark yellow, gray, pink diamond, black and so on. Diamonds are classified according to the color set by GIA, American Gemological Institute, from "D" (transparent and colorless, starting with the initial of the diamond) to "Z" (yellow).
Colored diamond is a kind of rare and extremely expensive diamond. The color grading system is not suitable for colored diamonds.
How to see the fineness of diamonds?
The quality of any finished diamond can be evaluated by these four standards. They are weight (carat), color (color), clarity and cut, so they are called 4C classification.
For consumers, according to their own preferences and budgets, the size of the diamond they want to buy is basically determined at the beginning, that is, the weight of the diamond.
Then what can give consumers the most intuitive feeling is color. The color classification of diamonds is expressed by the English letters of D-Z. Generally, the economically valuable color on the market is D-N, that is, 1 1 color scale. Diamonds below N grade have obvious yellow tone and poor fluidity, which affects the beauty of diamonds. In this 1 1 color scale, H color is the watershed from transparent colorless to yellow tone, and its color is between yellow tones, with or without it. After the H color, there are more and more yellow tones of diamonds. Consumers can choose diamonds with more than H color (including H color) when choosing colors.
Cutting is the second life of diamonds, and high-quality cutting unions make diamonds shine. The evaluation of diamond cutting is determined by cutting, polishing and symmetry. Every aspect can be divided into five grades: ideal tangent (EX), very good (VG), good (G), fair (F) and poor (P). The better the cut, the more light that enters the diamond is reflected, and the more beautiful the diamond is. Consumers should choose diamonds above VG from three aspects.
The clarity of diamonds is that professionals observe and grade the clarity of internal inclusions and external features of diamonds under a magnifying glass of 10 times. The higher the clarity, the cleaner the diamond. However, these are invisible to the naked eye, especially the diamonds with a size over SI2. Cleanliness has no influence on the wearer, so as long as Si/Kloc-0 or VS grade diamonds are selected, the requirements of consumers can be met.
Which is more important, fineness or clarity? Help! !
For diamonds with a score of more than 30 points, you must choose an international certificate such as GIA, because it is shown on the standard certificate of each parameter. First of all, I think what you should pay most attention to is "cutting", cutting, polishing and symmetry. The three items are always called cutting work, which affects your whole diamond. 40% of the price is the only man-made factor that affects diamonds. There is a gap between different prices at each level. Judging from EX (perfect) VG (very good) G (good) F (general) P (poor), if all three are EX, the price will be very high and the most valuable, and then you need to know whether the diamonds marked by GIA certificate number are fluorescent. Fluorescent diamonds are cheap and have an impact on diamonds, so you must choose non-fluorescent diamonds.
Finally, back to your question, which is more important, color or clarity? In fact, both are very important, but according to the percentage of consumption, more people will choose diamonds with good color, because it is visible to the naked eye, and the better the color, the more transparent the diamond is, and the clarity is invisible to the naked eye. If the general budget is enough, it is best to control the carat diamond at VS 1, and if it exceeds the budget, you can choose VS2. SI 1 is also acceptable. If you choose a color, you can choose D E F G, which is quite white. For example, the GIA certificate 1 carat VS 1 F color 3EX cutting has no fluorescence. The market price of this diamond ranges from 70000 to 65438+ 10000. If this diamond is not an international certificate but a national inspection certificate, the price will be greatly reduced, and the grade will only be displayed as 1 carat VS F-G, with no other parameters. It is not recommended to buy diamonds with this certificate, which has no appreciation significance and no diamond waist.
How to tell the fineness of diamond ring?
First of all, it depends on what color you want to choose. Platinum 990, platinum 950, palladium 990, palladium 950 and 18K. Platinum is the most expensive, almost 300 yuan per gram. Its natural color is white and will not change color for a long time. Platinum 990 is relatively pure and softer than platinum 950. Palladium is relatively cheap, about 0/00 yuan per gram/kloc, but it will turn black after wearing for a long time, because its natural color is not white, but it is white after electroplating.
18K will also change color, but it will last longer than palladium. Retail stores outside are generally sold by the gram, with many styles. Of course, the heavier ones are more expensive.
If you want, it's better to buy platinum, but 18K is also good, which is economical and has a good texture. Palladium is not so good. It will change color when worn for a long time, and it is soft and easy to deform.
Diamond ring color!
Let's first evaluate LZ diamonds: H color, white, a little higher than the I-J *** grade of general shopping malls, ok, not yellow, very good clarity VVS, which is extremely flawed, that is, it is difficult to see the inclusions under the magnifying glass of 10 times. 24 points, not very big, but can meet the needs of general decoration, because it is a finished diamond ring, there is no cutting parameters, so I will not make an evaluation here. According to the current international quotation, the price of such a diamond is 3 1, 7 1. 12 yuan, and the average female ring holder is about 2g, and the cost is about 400-500 yuan. The total cost of production, appraisal and packaging is less than 100 yuan. Generally, the retail price of diamonds in shopping malls is 3-4 times the cost, as long as the price bought by LZ is within this range, it is reasonable.
If the ring doesn't fit, you can change it. Prong setting technology is relatively solid, don't worry. LZ can buy from any merchant, and general retailers will provide this service ~