1, composition: mainly carbon C (99.95%) and other trace elements.
2. Physical properties:
(1) Hardness: H= 10, the hardest substance in nature, and its hardness is 150 times that of grade 9 ruby and sapphire.
(2) Color: mainly colorless white and yellow, brown, pink, blue, green, red, brown, black and other colored diamonds, which are very precious and rare.
(3) Dispersion: the dispersion is high (0.044), and after processing and polishing, the fire reflects colorful light.
(4) Glossy and transparent: diamond luster, transparent to opaque.
(5) Thermal conductivity: Thermal conductivity is very high in nature and can be identified by thermal conductivity meter.
3. Identification method:
(1) luster: unique diamond luster.
(2) Density: 5.95g/cm3, which is mainly identified by bare diamonds and weighed by hand, which is heavier than other gems of the same size.
(3) Fire color: The perfect diamond fire color is jumping, bright but soft, and artificial cubic zirconia and other imitation diamonds also have fire color but dull and monotonous.
(4) Hydrophilicity and hydrophobicity: lines can be drawn on the diamond surface with an oil pen, while the lines drawn with a water pen are intermittent, and a clear handprint can be left after being touched by hand.
(5) Ridge: The ridge between the hard facets of natural diamonds is straight and sharp, and the imitation ridge is smooth and has protrusions.
4. Place of origin:
Australia, Angola, Zaire, South Africa, Botswana, Namibia, Russia, Canada, India, China.
Australia has the largest output, and China is produced in Shandong, Liaoning and Hunan.
5.4c Evaluation:
(1) color (color)
D 100 extremely white
E 99 is extremely white
F 98 youbai
G 97 youbai
H 96 white
I 95 is yellow and white
J 94 yellow and white (brownish gray)
K 93 light yellow and white
L 92 light yellow and white
M 9 1 light yellow
N 90 light yellow
(2) clarity
All defects of diamonds are called defects, which are divided into internal defects and external defects. In the sales process, defects are called inclusions or inclusions.
A internal defects: crystal inclusions, clouds, point group inclusions, pinnate veins, internal growth lines, cleavage, internal protocrystal planes, cavities, notches, impact marks, laser holes and whiskers.
B external defects: original crystal plane, external growth line, scratch, polishing line, burn mark, extra facet and edge line wear.
C, grading
A) Flawless grade (FL): Under the magnification of 10, there are no flaws inside and outside the diamond.
B) Internal Flawless Grade (LC): Under the magnification of 10, the diamond has no flaws inside, and there may be slight flaws outside.
C) Very tiny flaw grade (VVS): diamonds have tiny flaws, which can hardly be observed under the microscope of 10 times. Micro-point inclusions, cloud inclusions and growth lines are divided into VVS 1 and VVS2.
D) Defect level (VS): There are small defects, which are difficult to observe under the microscope of 10 times. It can be divided into VS 1 and VS2, which are invisible to the naked eye.
E) Defect grade (SI): The defects of diamonds are very small, which can be easily found under the microscope of 10 times, and can be divided into SI 1 and SI2, which are difficult to find with naked eyes.
F) Defect grade (I): 10 times, which can be clearly seen by naked eyes under a microscope. It can be divided into I 1 which does not affect brightness, I2 and I3 which affect brightness and transparency.
(3) cutting
A) Standard cutting can make the diamond dazzling, otherwise improper cutting ratio will greatly affect the brightness and fire color of the diamond, making the diamond dull and colorless. A standard round diamond is cut with 57 to 58 facets.
B) The cutting shapes are round, oval, olive, water drop, heart, princess and emerald.
C) Four cutting centers: Belgium/Antwerp, USA/new york, Israel/Tel Aviv and India/Mumbai.
D) Evaluation criteria: If the proportion is too small, the fisheye effect will appear; If it is too thick, a black matrix will appear.
(4) carat weight
1 g =5 carats 1 carat =0.2 grams 1 carat = 100 integral.
Finally, learn about diamond certificates, including GIA NGTC HRD CTA IGI NGGC GIC, etc. Most of China's certificates are NGTC, and GIA IGI's recognition is the highest in the world.