Lately, we’ve heard a few jewelers in our shop express confusion over whether they should order platinum alloyed with iridium, or ruthenium. Both iridium and ruthenium belong to the platinum family of metals, but they confer different benefits when alloyed with pure platinum. Here, we’ll discuss the differences between the two alloys.
Historically, platinum was always alloyed with iridium; generally using a mixture of 90% platinum and 10% iridium. This alloy has become less popular in recent years. The most common casting grain we sell is 95% platinum alloyed with 5% ruthenium.
Generally, 950 platinum-iridium alloy is soft and malleable. This makes it easy to work with, but it’s vulnerable to dents, scratches, and deformation. So while it’s great for hand fabrication and small pieces of jewelry, it doesn’t hold up well over time.
950 Platinum-ruthenium alloy is the opposite. It’s resistant to wear and tear, but because its hardness is so much higher than platinum-iridium, it’s difficult to mold and takes greater skill to work with to avoid cracking it under excessive pressure. If you can mold platinum-ruthenium without cracking it, it lasts for a very long time. This makes it a great alloy not just for jewelry, but also industrial-grade parts.
Ruthenium also trades at a much lower price per ounce than iridium, so ruthenium-based alloys cost less. If you want to create platinum pieces that last longer and cost less, choose a platinum-ruthenium alloy. If you want a more “classic” platinum that’s easy to work with and builds character over the years, choose a platinum-iridium alloy.