The most difficult part of creating a Black Sapphire is in the heat treatment process. Deciding which heat treatment process was the best was a difficult decision and required lots of research. Mr. Phimla had some knowledge and experience in heat treatment of sapphires as an apprentice with his teacher. He had known for a long time that his teacher was the best and most experienced craftsman for heat treatment of black sapphires, but shied away from the limelight. After checking around for the best craftsman in heat treatment, it turns out that there were only 3 of them, all in Chantaburi province. All three teachers graciously shared heat treatment techniques to perfect a black sapphire. Applying the knowledge and expertise from all teachers, Mr. Phimla perfected his own techniques to develop black sapphires that matched market preferences.
The second challenge was to find the best source of rough stones to make the perfect black sapphire. There were many choices: from China, Australia, Vietnam, Laos, and Afghanistan. It turns out that the best stone for black sapphires were from Thai and Laos, but they were quite difficult to find. Sapphires from Afghanistan were the least black. Sapphires from China, Australia, and Vietnam were similar in color and quality and were in abundant supply. Consequently, CBS sapphire sources are from China, Australia and Vietnam.
After concluding the best heat treatment technique and source of rough stone, Mr. Phimla flew to Shianghai and Shingtao to buy rough stones. The stones were mined out Changlue subdistrict, Weifang district in Shandung province. The journey started with a 4 hour flight to Shianghai, followed with a short flight to Shingtao, and a 5 hour road trip to Weifang. The stone mines were still another 1 hour road trip away in the subdistrict of Changlue which is China’s largest source of sapphire. This was a well traveled route for Mr. Phimla after having dealt with Changlue sapphires for more than 10 years.
To buy sapphires in Changlue required a stop at a friend’s house where stones are presented and negotiated. A decision to buy is made only after viewing stones from at least 4-5 merchants. After viewing stones from about 200 merchants in 3 days, the first lot was purchased totaling about 200 kilograms of stone. The products were shipped via air freight. Stones over 1 metric tons are shipped via sea freight.
Arriving at the factory, the stones enter CBS’s manufacturing process as follows:
1- Cleaning of the rough stone with liquid dish detergent to rid of grime and dirt and air dry
2- Screening out stones that are not sapphires and classifying the usable stone by size. The size will determine the method of heat treatment. Larger stones are heat treated from the bottom to the top, whereas smaller stones are heat treated from the top to the bottom.
3- Heat treatment. Whether to treat the stone with oil, gas, or electric stoves, will depend on the size and the physical characteristic of the stone.
4- Grading of the black stones choosing the most even dark color for further processing.
5- Slicing to get the best color and presentation.
6- Pre-form. CBS ensures that every stone will be pre-formed to deliver the best black color, even if it means a smaller stone. Many factories want to keep the stone as large as possible during the pre-from resulting in a stone with an uneven color. This is the most important step of the process and difficult to find skilled craftsmen.
7- Cutting. CBS cutting technique matches international standards for fine jewelry and the size of the gem must meet size standards.
8- Polishing. CBS polishing brings out the best facets in the gem and matches international standards for fine jewelry. This stage requires expert craftsmen who are more expensive.
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9- Product costing. Because each stone is different, the cost is also different
10- Grading. Black Sapphire by CBS has 3 grades as follows:
- B1 : shiny even black color top and bottom
- B2 : shiny black color, even black top and slightly colored bottom
- B3 : slight unevenness of black color
Our 2mm and smaller round gems are available in 2 quality grades for customer selection: 1) cut manually 2) cut by machine. The machine cut gems are suitable for jewelry pieces that require high precision in the designs and are priced higher.
11-Inventory management and ready for sale