Diamond color (color)
The color of a diamond refers to the colorless degree of the diamond.
For most precious diamonds, the identification standard of color depends on its colorless degree. A diamond with perfect structure and no impurities, like pure water drops, is colorless and of high value. GIA established a D-Z color grading system, and passed the
Under precisely controlled lighting and observation conditions, diamonds are compared with "colorimetric gems" to determine their colorless degree.
GIA's D-Z color grading system is the most widely used grading standard in the industry. D is the highest color scale of a diamond, which means it is completely colorless. From D to Z, with the deepening of color, the grade of diamonds gradually decreases.
Although the color difference between diamonds is too subtle for non-professionals to distinguish, it will cause great differences in the quality and price of diamonds.
Clarity of diamond
The clarity of a diamond refers to the degree to which it has no inclusions and surface features.
Natural diamonds are formed by carbon at high temperature and high pressure. This process also leads to the internal characteristics of each diamond, which are called "inclusions", while the characteristics of the diamond surface are called "surface characteristics".
The evaluation of diamond clarity includes identifying the number, size, visibility, type and location of the above features, and their influence on the overall appearance of the diamond. Although there is no perfect natural diamond in the world, the higher the clarity, the higher the value.
GIA diamond clarity standards are divided into six categories, 1 1 grade.
Flawless grade (FL):
Under the magnifying glass of 10 times, diamonds have no inclusions and no surface features.
Internal defect-free level (if any):
Under the magnifying glass of 10, there is no inclusion in the diamond.
Very slight inclusion levels (VVS 1 and VVS2):
Under the magnifying glass of 10 times, there are tiny inclusions in the diamond, which is difficult for even professional appraisers to see.
Slight inclusion level (VS 1 and VS2):
Under the magnifying glass of 10 times, there are tiny inclusions in the diamond.
Micro-inclusion levels (SI 1 and SI2):
Under the magnifying glass of 10 times, the diamond has visible inclusions.
Inclusions (P 1, P2 and P3):
The defects of the diamond can be clearly seen under the magnifying glass of 10 times, which may affect the transparency and luster of the diamond.
Diamond cutting method
The high refractive index creates the brilliant light of diamond, making it famous all over the world. Many people will equate the diamond cutting type with the diamond shape (round, emerald square, pear shape). In fact, the cut level of a diamond depends on the interaction between its facet and light.
From the original stone to the finished diamond, it needs complicated working procedures and exquisite cutting skills. Only after careful cutting and grinding ratio, symmetry and polishing can the unique brilliance of diamonds be perfectly displayed.
Cutting is very important for the appearance and value of diamonds, and it is the most complicated and technically demanding appraisal standard in 4C standard.
In order to determine the cutting grade of standard round brilliant cut diamonds (the most common shape in diamond jewelry), GIA will calculate the proportion of each facet, which will affect the front appearance of diamonds. Therefore, GIA can identify the degree to which each diamond forms brilliant visual effects under the interaction of light and facets:
Brightness: White light reflected inside and outside the diamond.
Fire color: White light is decomposed into colorful spectral colors.
Flash: the form of bright and dark areas caused by the flash produced by diamonds and the reflection of light inside diamonds.
In addition, GIA's cutting grade appraisal also includes the evaluation of diamond design and cutting technology, such as the relative ratio of diamond to diameter, waist thickness (which can affect the durability of diamond), the symmetry of facets and the polishing quality of each facet.
GIA's cutting evaluation of D-Z standard round drill includes five grades: excellent, very good, good, average and poor.
Diamond carat weight (carat)
Carat is a unit to measure the weight of diamonds. 1 carat equals 200 mg.
When measuring the weight of diamonds, 1 carat is equivalent to 100 "minute", thus making the carat weight accurate to two decimal places. Jewelers can directly use "cents" to describe a diamond weighing less than 1 carat. For example, a 0.25-carat diamond is also called "25 cents". Diamonds above 1 carat can only be described as "carat" accurate to 1%. For example, a 1.08 carat diamond can only be described as "1.08 carat".
Remember, the value of a diamond depends not only on its carat weight, but also on the 4C standard * * *, which is indispensable.