Boiling is one method of cleaning diamonds. Diamonds must be checked at every stage of manufacturing and sorting to determine what defects remain.
At some stages of the manufacturing process, dirt sticks to the diamond’s surface, which can be traces of adhesive, dust from polishing, or other things. At the end of the manufacturing process, before they are sorted as polished, diamonds undergo a boiling process – basically, “cooking” that removes all the foreign substances stuck to the diamond. There are two kinds of boiling – regular and deep boiling, also known as deep cooking.
Regular boiling
Regular boiling is intended to remove external dirt only, and is conducted at various stages of the polishing process as the polisher determines necessary to continue the process. Boiling is done is special rooms.
Special test tubes are set up in special ovens, into which diamonds are placed. If the stones are large, they are put in individually; if the stones are small, they are placed in packets. Sulfuric acid is poured into the test tubes along with a potassium chloride mixture. Diamonds are not affected by acid and are therefore not harmed. The diamonds are then “boiled” for about 15 minutes, until the potassium chloride dissolves and the liquid turns yellow.
The diamonds are then removed from the oven, cooled, washed with a great deal of water, and then with spirit and tried well with cloth towels. Every diamond is then returned to its brifka. At the end of the process, the diamonds are sparkling and bright, clean from any remaining external dirst.
Deep boiling or deep cooking
The purpose of deep boiling is to try and reach internal dirt, which the boiling materials can reach via a tiny crack known as an “open inclusion” the tiny bit of black graphite (“fix” as it’s known by diamantaires) trapped inside the diamond. These tiny dots are trapped in the diamond when it is formed. Since acid doesn’t corrode the diamond itself, but only the dirt that has entered the stone, the process allows dirt to be removed so the polished diamond looks better.
Deep boiling is a long process that lasts 10-12 hours. It is done using a mixture of extremely strong acids, at high heat. Diamonds are placed in very strong containers made of tantalum and are then sealed in pressure containers. After the boiling process, the containers are cooled, the remaining acid steam is released, and the diamonds undergo another regular cleaning process. The deep boiling process is more complicated and more dangerous than regular boiling.
Courtesy of Talking Diamonds: A Lexicon of Diamond World Technology by Shalom Lissitzky
FAQ Boiling Diamonds – Method of Cleaning Diamonds
What is the purpose of boiling diamonds during the manufacturing process?
Boiling is a cleaning method used to remove foreign substances that stick to diamonds during various stages of manufacturing and sorting. This includes traces of adhesive, polishing dust, and other dirt that accumulates on the diamond’s surface. The process is essential for preparing diamonds for final sorting as polished stones, ensuring they are sparkling, bright, and free from any remaining external dirt. Diamonds must be checked and cleaned at every stage to determine what defects remain and to maintain their quality.
How does regular boiling work and what materials are used?
Regular boiling is conducted in special rooms using test tubes placed in special ovens. Large stones are placed individually while small stones are put in packets. The diamonds are submerged in sulfuric acid mixed with potassium chloride and “boiled” for about 15 minutes until the potassium chloride dissolves and the liquid turns yellow. Since diamonds are not affected by acid, they remain unharmed during this process. After boiling, the diamonds are removed, cooled, washed thoroughly with water, then with spirit, and dried with cloth towels before being returned to their containers.
What is deep boiling and how does it differ from regular boiling?
Deep boiling (also called deep cooking) is a more intensive process designed to reach internal dirt through tiny cracks called “open inclusions” that can contain black graphite particles trapped during diamond formation. This process lasts 10-12 hours and uses extremely strong acid mixtures at high heat. Diamonds are placed in very strong tantalum containers and sealed in pressure containers. The process is more complicated and dangerous than regular boiling, but it allows acid to reach and remove internal dirt that regular boiling cannot address, making the polished diamond look significantly better.
What safety measures and equipment are required for diamond boiling processes?
Diamond boiling requires specialized equipment and safety protocols, particularly for deep boiling. Regular boiling uses special test tubes in special ovens within dedicated rooms. Deep boiling requires much more robust equipment including very strong containers made of tantalum (a highly corrosion-resistant metal) and pressure containers to seal the diamonds during the lengthy process. After deep boiling, containers must be properly cooled and acid steam safely released before diamonds undergo additional cleaning. The deep boiling process is specifically noted as being more dangerous than regular boiling due to the extremely strong acids and high heat involved.
