Dr. Yuan: Cutting of Lab-Grown Diamonds

专栏 · 苑博士讲钻石

Column: Dr. Yuan Chat Diamonds

The cuttings of Lab-Grown diamonds are basically similar to the cutting methods of natural diamonds.

Most of the major mining countries of natural diamonds stipulate that the rough diamonds dug in the country must be processed into finished diamonds in the country before they are allowed to be exported. This can increase their employment opportunities and increase the value of the diamonds. Lab-Grown diamonds are produced in China at a very high rate. We can leave large size Lab-Grown rough diamonds in China for cutting. This can increase the value of Lab-Grown diamonds. Medium and small-sized rough diamonds are not worth processing in China.

The value of Lab-Grown diamonds is much lower than that of natural diamonds. Therefore, when cutting, we must try our best to reduce costs. We can use automatic equipment to do the processing as much as possible, including: the rough automatic three-dimensional designing instrument, finish the designing, and then use laser to mark the table and girdle lines on diamonds. Use the laser to cut planes, shapes, and digging gyros (or 4P) along the laser lines. In the future, there will be laser to cut out every facets of round and fancy shapes, automatic girdling machines, automatic blocking machine, automatic polishing machine, technology manual polishing.

1. Rough stone design, three-dimensional designing instrument.

2. Laser sawing the rough diamonds, laser cutting machine

▲ Laser cutting plane

▲ Laser digging gyro

▲ Digging the gyro

▲ Dogged gyros

3. Diamond wheel automatic girdling machine

4. The automatic diamond polishing machine made in Israel, must be polished one by one, not multiple diamonds together

5. Fine polishing, technical manual polishing

Lab-Grown diamonds have a lower average cost than natural diamonds, with larger sizes and better quality. Almost all of them can be cut and polished to obtain an excellent proportion grade, polishing, and symmetry. They are easy to be cut into various fancy shapes and processed into various colors.

There will be polycrystalline diamonds around the surface of CVD-grown diamonds. Before polishing the diamonds, all polycrystalline need to be completely removed with a laser. Then cut CVD diamonds in the same way as natural diamonds. If the polycrystalline are not completely eliminated in the initial shape, the subsequent cutting and polishing works will be very difficult, because each polycrystalline diamond is a diamond crystal in a different direction, which is difficult to be polished.

When all diamond finish polishing each facet with the automatic polishing machine, the edge of the fixture will be electrically conductive when it comes into contact with the grinding disc. The machine knows that this facet has been done, and will automatically lift to the next facet to continue polishing. However, colorless HPHT diamonds have semi conductivity properties and cannot be processed by automatic polishing machines. An insulating ceramic sleeve can be added, but this kind of operation is more difficult, and it is only suitable for processing blocking bottom and crown.

At this stage in China, it is suitable for processing larger diamonds of more than one carat of polished, medium and small-sized rough diamonds must be processed by factories in India that are more skilled in processing medium and small-sized diamonds.

Author

Joe Chih-Chung Yuan, Ph.D. from Sun yat-sen university, Director of Henan Godiam New Material Technology Co., Ltd. Engaged in diamond cutting , identification, researching teaching and growing for more than 44 years. Currently engaged in diamond jewellery cutting, high temperature high pressure(HPHT), chemical vapor deposition (CVD) single crystal, polycrystalline diamonds growing, application researching and production. Established laboratories and diamond cutting and growing factories in New York, Taipei, and Zhengzhou.

- Obtained the GIA Graduated Gemologist G.G.
- Obtained the D.G.A diamond membership and tutor qualification of British Gem-A.
- Dozens of new diamond design patterns and invention patents in various countries around the world
-In 2009, became a delegate of the International Gemmological Conference(IGC), the highest gemmologjcal conference in the world.
- Hundreds of presentations and dozens of papers in Chinese and English in professional journals in various countries.
-  Publication: "Diamond Researching" was published in New York, USA in 1999.

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