During the production of synthetic diamonds, metals such as iron, cobalt, and nickel are used as catalytic materials. Especially when iron-based catalysts are used, tiny metal particles can easily get trapped inside the diamond crystals as they grow. The more metallic impurities trapped inside a diamond, the stronger its magnetism becomes. These residual metallic impurities act like hidden internal flaws: they not only disrupt the intact structure of the diamond crystal, but also make it much more prone to cracking under heavy pressure and high heat.

Experimental tests show that the stronger a diamond's magnetism is, the less pressure it can withstand. A single high-quality diamond crystal can bear a load of eighteen or sixteen kilograms, whereas as internal magnetic impurities increase, its compressive strength drops steadily to twelve to fourteen kilograms, ten to twelve kilograms, and in the worst cases, down to only about eight kilograms. In other words, the level of magnetism directly reflects the amount of internal impurities: stronger magnetism means lower compressive strength, poorer crystal integrity, and much worse heat resistance during subsequent high-temperature blade manufacturing and high-speed stone cutting.

To verify the effect of removing magnetic particles, researchers conducted a comparative test. They took a batch of standard diamond raw materials—labeled with a nominal strength of sixteen kilograms and an actual average strength of seventeen point two kilograms—and used magnetic separation equipment to divide them into two groups: one group of strongly magnetic particles and another group of pure, nearly non-magnetic particles, each accounting for about forty percent of the batch. Testing revealed that the sorted-out magnetic diamonds could only withstand an average of sixteen point three kilograms, while the remaining pure, non-magnetic diamonds reached an average compressive capacity of eighteen point eight kilograms. Through this single magnetic separation step alone, the non-magnetic diamonds achieved a fifteen percent higher strength than the magnetic ones.

When these two types of diamonds were made into large circular saw blades measuring one point six meters in diameter using the exact same formula and manufacturing process to cut granite, the difference in actual service life was striking. Saw blades made from unsorted or highly magnetic diamonds could only cut an average of one hundred and sixty to one hundred and eighty square meters of stone. In contrast, saw blades made from the magnetically purified, non-magnetic diamonds saw their average cutting area jump to two hundred and thirty square meters. This clearly demonstrates that sorting out strongly magnetic impurity particles before manufacturing makes the saw blades far more wear-resistant, sturdy, and durable when cutting hard stone.