There is a reason why 'platinum' is atop of the record-selling charts. And not simply because it is expensive. Considered an extremely rare metal, why else would platinum be so desirable, especially when producing pens?
Platinum has a higher luster and a better overall durability than sterling silver or gold. Every time other metals are scratched or polished, a tiny bit of the metal is lost. Although platinum can be scratched and develop a patina of wear, the metal is so strong that it will not chip or splinter. It also does not tarnish in air. The metal resists corrosion and high temperatures, yet is malleable enough for a jeweler or pen-maker to work with. With a simple polish, the finish on a platinum piece can be brought back to its original lustrous shine.
Platinum has several industrial uses, most notably as part of vehicle emissions controls on catalytic converters, oxygen sensors and spark plugs.
Platinum is plated on most pens that feature the material. The plating varies in thickness and purity. The choice of platinum as the exterior of a pen is done to increase durability and to imbue the creamy, silvery luster as part of the aesthetic qualities of the design. Some fountain pens may use a solid gold nib with a platinum mask to match the nib color with the trim or body color of the pen. In more affordable models, platinum is plated on the clip and trims.
See our previous post in the series, It's All Material, the Gold Standard