The 4C grade of diamond refers to:
For us.
transparency
Cutting incision
Weight carat
The origin of 4C means that the first letter of the above four English words is "C", so people's classification of diamonds is simply called 4C classification or 4C evaluation. At present, it is a universal standard for diamond classification all over the world.
Many customers may ask? Which "C" is more important when evaluating diamonds?
In fact, in 4C evaluation, every factor is very important and plays a key role in the final price of diamond products. When other factors are close, the most important thing is the total number of carats of diamonds. The bigger the diamond, the rarer it is. Therefore, weight plays an important role in determining the price of a diamond, which is why customers are often seen to measure the price.
After understanding the above, we will learn from
1, weight carat? Start learning:
1 carat is equal to 0.2g, which is commonly expressed by Clutton (ct). Kela in Greek comes from "keration", which means carob tree. This is a plant that spreads widely from East Asia to the Middle East. Because it is said that its fruit weight is almost the same, carob is used as a unit of weight for jewelry and precious metals. Once you have determined the cut, color and clarity of the diamond, it is easy to find the diamond with the corresponding price according to your budget. ?
The weight of diamonds is very important in diamond classification. The weight of diamonds is measured in carats. The word "carat" comes from the seed of a tree called "small horn tree". Because the weight of this seed is surprisingly consistent, each seed is one carat, so it was used to weigh diamonds in ancient times. The current national standard is 1ct? =? 0.2g, one carat equals 100 cent, for example, a 25-cent diamond can be recorded as 0.25 carat. Diamonds of the same quality, the greater the weight, the more precious.
The weight or size of a diamond is measured in carats (ct). 1ct？ =? 0.2? G, and 1ct= 100 integral (pt) (or equivalent to 200mg). The electronic balance with an accuracy of 0.000 1ct can be used to weigh the precise weight of diamonds, and the mechanical balance can be accurate to 0.00 1ct, which is the international common gem quality unit. Finished diamonds are required to be accurate to two decimal places, the third decimal place of carat value is one ninth, and others are ignored.
Summary: More than 25 points have the value of preservation. Money can buy more than 30 points, and money can buy more than 50 points.
2. Cutting and cutting
The various optical effects of diamonds are determined by the shape of diamonds and the angles between various faces. The quality of cutting only directly affects the beauty of diamonds. From the following 4C classification, we can also see that any nonstandard cutting evaluation factors will affect the brightness and aesthetics of diamonds to varying degrees. ?
If the mesa is too small, the brightness of the diamond will be greatly reduced; Too big a watch will greatly weaken the fire color of diamonds.
If the cutting is not good, the various optical effects of the diamond can not be fully exerted, and the brightness and fire color of the diamond will also be reduced.
H & ampa cutting (Cupid cutting = = eight arrows and eight centers) is a special cutting method, which overlaps the geometric shapes of the star facet and the pavilion main facet, and cuts eight arrows and eight centers from the desktop and the bottom respectively. The eight arrows and eight hearts cut by H & ampA can only be seen by magnifying observation with a cutting mirror. This special cut is usually a very good cut, because the standard cut specifies a data range, not a single data. The cutting of diamond is the optical key to fully highlight its fire color and reflect the deep shining light of diamond; A carefully cut diamond, no matter what shape or grade, can be full of brilliance and flame; Diamonds with proper cutting ratio have higher natural value.
The width and depth of diamonds have a great influence on the fire color of diamonds.
Cut the pavilion too shallow: the light escapes from the bottom, creating a fisheye effect-the diamonds are lighter in color. ?
Cut the pavilion too deep: light can easily escape from the pavilion, resulting in a black background effect-it looks like diamonds are black. ?
Ideal cut: represents the standard that only 3% of first-class high-quality diamonds can reach. This cutting makes the diamond reflect almost all the light that enters the diamond. ? Elegant and excellent cutting.
Very good cut: represents about 15% of the diamond cut. It can make diamonds reflect the light of standard grade cutting, but the price is slightly lower.
Good cutting: represents about 25% of diamond cutting. Diamonds reflect most of the light that enters them. Much cheaper than VG.
General cutting: it means that diamonds with a roughness of 35% are still high-quality diamonds, but the light reflected by general cutting diamonds is not as good as that of G-cut diamonds.
Poor cutting quality: This includes all diamonds that do not meet the general cutting standards. The cut of these diamonds is deep and narrow or shallow and wide, which makes it easy for light to escape from the edge or bottom. We don't offer this kind of inferior cut diamond. ?
The cutting ratio affects the color and fire color of diamonds.
The proportion of diamonds means that the average diameter of the waist is 100%, and the percentage of other parts relative to it is the primary factor to measure the diamond cutting.
Commonly used diamond ratio is:
1. Desktop: the percentage of desktop width relative to the average waist diameter. Smaller watches and higher crowns have more fire colors; Larger countertops and shallower crowns have more brightness; The appropriate proportion is the balance between fire and light.
The percentage of pavilion depth relative to the average waist diameter.
The cutting workers whose pavilion depth ratio is less than 40% have fisheye phenomenon; The depth of the pavilion is 49%, and the shadow occupies the whole table, resulting in the phenomenon of black background.
3. Waist circumference: the percentage of waist circumference relative to the average diameter of waist circumference.
Too thick waist affects the color of diamond, and light leakage reduces brightness; Too thin a waist is easy to get hurt.
4.cuet: the percentage of the bottom diameter relative to the average waist diameter.
The bottom facet is too large, and the light incident from the front leaks out from the bottom facet, showing small black spots under the desktop; Diamonds without bottom facets, with sharp bottoms, are easily damaged during circulation and inlaying. When viewed under the table, the bottom facet shows a small white dot.
Polishing and symmetry of diamond are two important aspects in the cutting process. Polishing grade describes the smoothness of diamond surface, while symmetry grade refers to the arrangement of various facets of diamond. Polishing quality directly affects the optical effect of diamond. On the uneven surface, the light diffuses, causing the surface of the diamond section to be dull and colorless, giving off turbid or dim light. The deviation of symmetry makes the incident light or the light existing in the diamond itself not follow the designed path. Each diamond grading report clearly lists the polishing of the diamond cutting surface and the description of the symmetry grade. According to the GIA and HRD symmetrical grading standards, it is divided into ID (standard), EX (excellent) and VG (very good) G (good), and China's national inspection is divided into EX (excellent) and VG? (good), g (good) Do you want to avoid grinding and symmetrical class F? Or a p-diamond. Because the symmetry of the diamond section may greatly mislead the reflection and refraction of light, thus affecting the brightness of the diamond.
Many customers may ask what kind of cutting is the best.
For a diamond with the best cut, it looks very special when we look at it under a magnifying glass. You can browse the diamonds we offer. These diamonds reflect the most dazzling light because they are cut in the most accurate proportion. They have the most advanced polished and symmetrical round diamonds. They also have ideal and well-cut princess diamonds, emeralds and diamonds.
If you have a high-value bright diamond, you should choose VG or G-cut diamond with good finish (polished and symmetrical). If you want to have a standard cut, but also have VG or G degree of polishing and symmetry, you can consider choosing cheaper diamonds with slightly lower clarity and color, and it is easy to choose diamonds with G or H degree of chromaticity and VS 1 or VS2 clarity.
Summary: Generally speaking, there is only surplus in the market. And very? Good grades and higher grades are rare, and the price is much higher. It is suggested that all of the above can be considered, including good cutting.
Let's stop here about diamond cutting. What do VS 1 and VS2 mentioned above stand for respectively? Don't worry, don't worry. We will talk about it next.
3. Clarity
Perfect diamonds are the most popular and precious? . However, there are some inclusions, burn marks, mineral traces or other tiny features in many diamonds, which will destroy the purity of diamonds. ? By who? Few things are perfect in nature, and most diamonds are the crystallization of defects. Because the defect is inside the diamond, it is called inclusion, which includes:
Tiny bubbles? -"Cloud"? -Cracks
-Feathers? -Mineral inclusions
NGTC, GIA and HRD organizations use a series of detailed rules and standards to outline the quantity, origin, model and inclusion type of diamonds.
Specific standards as shown in the figure:
It was established on the basis of the contents of GIA and CIBJO, combined with the national conditions of China, revised on July 1 day, 2003, and implemented on July1October1day, 2003. The standard divides diamond clarity into five grades, namely 10: c; VVS 1、2？ ; VS 1、2； VS 1、2？ ; P 1、2、3
So what kind of clarity level is the best?
We suggest that you choose VVS diamonds that are invisible to the naked eye.
This kind of diamond has high value, but it is cheaper than IF, f and f diamonds, and it does not contain obvious defects, which will not detract from the beauty of the diamond.
If you want to choose a diamond with a purity of VS, you can call the jewelry consultation office to make sure that what is in the diamond is invisible to the naked eye.
But if the diamonds you want to buy are beautiful first and clean second, and you don't want to change your budget at the same time, you can choose cut SI-grade diamonds and G or H-grade diamonds, which are usually 4C combinations that are more suitable for you to wear, but not suitable for collection and preservation.
The following list will compare the prices of diamonds with the same carat weight, color and cut grade:?
Summary: f, IF:? The most rare thing is that 10 magnification is flawless and the interior is flawless. VVS 1, VVS2: tiny inclusions, tiny visual differences, which are difficult for professionals to detect after magnifying. VS 1，VS2，SI 1，？ SI2: Micro-inclusions, microscopic visual differences, which are extremely difficult to detect with naked eyes. I 1，？ I2，？ I3: There are inclusions, which can be detected by naked eyes. It is recommended to buy VVS. Generally, less than VS is not considered. SI 1 was not considered at first.
4, color color
Diamonds are equivalent to prisms. It can divide the light into colored lights and form colored flashes after reflection. Just as we wear colored glasses, the color of diamonds will act as a filter. Thereby reducing the escape of reflected light. The lighter the diamond color, the stronger the fire color (dispersion). The higher the color level.
Fluorescent? The intensity of visible light emitted by diamonds under the irradiation of long-wavelength violet light. Some diamonds will emit white, yellow or blue light under ultraviolet irradiation, which is called fluorescence effect. Ordinary non-professionals generally don't notice. Fluorescence effect is not an index to measure the quality of diamonds, but a characteristic of diamonds. China is divided into four grades according to the luminous intensity of diamonds under long-wave ultraviolet light: strong, medium, weak and none. Foreign countries are usually divided into negigibe, none, inert, weak, bue, strong? Six-level bue. If the fluorescence level is moderate or strong, the nearly colorless diamond surface can look whiter at a certain distance, thus adding a hazy or oily feeling to the diamond. The price of diamonds with medium or strong fluorescence is lower than other diamonds. ?
Which color scale is the best?
The following table is a comparison table of reference prices of diamonds with the same clarity (VSI) and carat weight (1 carat):?
For idealists, it is best to look for colorless diamonds with D-F grade and diamonds with four fluorescence grades of "strong", "medium", "weak" and "none".
For diamonds with high value and invisible color, you can buy diamonds with color grade G-J close to colorless, medium fluorescence grade or blue and white.
Furthermore, if you don't want to compromise on color but don't want to exceed the budget, you can choose a diamond with good cut, clarity of VS 1-VS2 and strong fluorescence, which is not inferior to the naked eye. It is possible that you prefer the unique effect created by fluorescence.
Summary: generally, it is best to buy F-G, and the second point is H? , and then I-J. Colors below I-J are basically not recommended.
Types and differences of diamond ring holders
First,? Platinum (white? Gold)
The so-called K platinum and platinum in the market are actually alloys of gold, nickel, copper and zinc. Theoretically, the gold content of 24K gold is 100%. With the decrease of gold content, the contents of 22k, 20k, 18k and 14K per 1k are1/24×100% = 4.16%.
Due to the addition of different metal elements, K gold can appear in many colors such as yellow, white, red and green. 18K gold has a gold content of 75% regardless of its color.
White gold has good reflectivity and is not easy to lose luster. Moreover, white gold has a high hardness and is often used to embed precious stones and jewelry.
II. Platinum (Platinum)
Also known as pure white gold, positive platinum or true platinum. But these names are unreasonable and easily confused with platinum. Its logo is Pt, silver gray and white. Pure platinum is relatively soft, and the addition of metals such as ruthenium, rhodium and palladium will increase its hardness.
Third, platinum alloy (platinum? Alloy)
Refers to the alloy of platinum mixed with other metals such as palladium, rhodium, yttrium, ruthenium, cobalt, osmium and copper. Although the hardness of platinum is higher than that of gold, it is not enough for inlay, and it must be alloyed with other metals before it can be used to make jewelry. ?
The seal of platinum ornaments in the world is Pt, Plat or Platinum, which is expressed by a few thousandths of purity, as follows.
1. foot platinum: the platinum content is not less than 990, and it is marked with "foot platinum" or "Pt990". ?
2.950 Platinum: The platinum content is not less than 950, and it is marked with "Platinum 950" or "Pt950". ? Does Pt950 contain palladium, rhodium and iridium? 5%, the hardness is still relatively low, generally used for plain platinum jewelry;
3.900 Platinum: The platinum content shall not be less than 900, and it shall be marked with "Platinum 900" or "Pt900". ? Pt900 contains 10% palladium, rhodium and iridium, and its hardness can be used for inlaying ornaments.
Fourth, palladium (palladium)
It is platinum, silvery white, with the symbol Pd, which is lighter and slightly harder than platinum. Specifications are marked with Pd 1000, Pd950 and Pd900. In terms of price, palladium is much cheaper than platinum; In terms of texture, palladium is light and brittle, while palladium jewelry is easy to fade, deform and wear after being used for a period of time because of its strong chemical properties of absorbing gas. Based on the above characteristics, the color of palladium jewelry will darken after wearing for a period of time.
Ring holder of diamond ring: platinum
China's platinum group mineral resources are few, the reserves are less than 1% of the world's reserves, and it basically depends on imports. Although more than 60 countries have discovered and mined platinum ore, its reserves are highly concentrated in South Africa and the former Soviet Union. Their total reserves account for 98% of the world's total reserves. The annual output of platinum in the world is only 85 tons per year, far less than that of gold. In addition, platinum has a high melting point, so it is more difficult to purify and smelt than gold and consumes more energy, so its price is also higher than that of Huang Jingui. It takes five months to extract one ounce of platinum from 65,438+00 tons of platinum ore. In mineral classification, platinum group minerals belong to natural platinum subgroup, including natural elemental minerals such as iridium, rhodium, palladium and platinum. There is a wide range of isomorphic substitution between them, thus forming a series of isomorphic mixed crystals. At the same time, its components often contain isomorphic mixtures of iron, copper, nickel and silver. When its content is high, it constitutes the corresponding species. Metals smelted from platinum group minerals include palladium, rhodium, iridium and platinum. All precious metals leave scratches, including platinum. However, the scratches on platinum only move the metal and will not reduce its volume, while the scratches on gold will bring wear and reduce the volume of gold. If there are visible scratches on platinum, qualified jewelers can re-polish it without damage.
Platinum is elegant and luxurious, symbolizing purity and nobility. Therefore, people regard it as a symbol of love and make engagement rings to show that love is pure and eternal. If diamonds are set in silver-white platinum supports, sparkling diamonds and dazzling platinum complement each other, setting off the whiteness, preciousness and elegance of diamonds. Egyptian priestess's coffin is decorated with hieroglyphics made of platinum, which can maintain perfection for a long time without losing its original luster, fully proving the durability and stability of platinum. Platinum didn't start to glow until the first diamond was dug up in Kimberly Mine in South Africa. The world-famous Hope diamond is always set in a platinum chain. In foreign countries, many people think that setting diamonds with gold may lead to the yellowing of diamonds, thus greatly reducing the price of diamonds. Diamonds inlaid with platinum can keep the pure white color of diamonds, especially as engagement rings. Diamonds inlaid with platinum are white and crystal clear, symbolizing eternal and long-lasting pure love. However, although the hardness of platinum is higher than that of gold, it is still not enough to set diamonds and jewels. It is often necessary to mix other metals to make platinum alloy to set diamonds.
Suggestion:? Please choose Pt950 for wedding diamond ring.
Reason one: the highest quality can best represent your mind and taste;
Reason 2: the quality is the most stable, avoiding the trouble of fading (changing);
Reason ③ The application is the most common, which is convenient for future modification and maintenance.
I hope you can sell a good diamond ring that your mother is satisfied with. Bless you!