The only white (gray) precious metal I have ever seen on the board, itself, was rhodium plated fingers on some Xerox boards from the 70's, which are as rare as hen's teeth. In modern boards of the "green" age, you might find a little silver in the solder. On the board, itself, you're looking for yellow gold. White gold isn't used on boards. Neither is Pt, Pd, Os, Ir, or Ru.
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A story. In the 70's, memory disks were standard on big business computers. These were set on stacks, not unlike records stacked up on a record changer. Some of these were as large as 48" in diameter. They were made of about 1/4" aluminum. A magnetic layer of electroless cobalt (usually) plating was laid down and a fairly heavy layer of some precious metal was laid down on top of that, to protect the magnetic layer. They usually used gold but they would have liked to use one of platinum metals because of their hardnesses.
The biggest thing going on in the memory disk industry was rhodium. Rhodium's properties were perfect. Better than sliced bread. A man that eventually became my partner in another venture was the leader in this. He had the world's largest rhodium plating bath. I worked for the company that sold him the rhodium solution and that's how I met him. It was a huge sale and I spent several days helping to set it up and we did lots of experiments to perfect it.
All went great for a few months and then they started have reading problems on the disks. In seems that pure clean platinum group metals tend to polymerize organics from the air. It was like strong rubber cement. Under the scope, I watched him roll it around in little brown sticky balls with an X-acto knife. It was so thin you couldn't see it just by looking at the disk.
In other words, it would be a mistake to use any of those metals for, say, fingers. The only other white PM is silver. It isn't used for fingers because it tends to form crystals that migrate on top of (or, through) the board material from one finger to another, connecting them.