The iridium particles are silver metal balls that are welded to the tip of the pen at high temperature and are in contact with the paper. Because it is more wear-resistant, it can reduce friction loss and increase the life of the nib during writing, so that the nib will not become thicker due to the wear and tear caused by a lot of writing. Different types of pens use different types of iridium particles. For example, steel-tipped pens (iridium pens) are easy to be corroded by ink because the nib itself is easily corroded by ink, so the selected iridium particles are usually cheaper and not wear-resistant, while gold pens are more wear-resistant due to the high value of the nib and its ability to withstand corrosion for a long time. The iridium particles can maximize their performance.

The grinding process and shape of the iridium grains give the nib a different thickness, feel and character. Some pens are also known for the unique shape of their iridium grains (eg Long Knife). Its polishing especially has a great influence on the advance and pause of Chinese writing.
Usually the color of the iridium particles is silvery white, but in some iridium gold pens the entire nib is yellow. This cannot be considered that there are no iridium particles, but the coating covers the iridium particles.