A platinum iridium ring is a stunning jewelry choice that offers the look and feel of gold, but with the durability and lustrous white color of platinum. It’s a great addition to any fine jewelry collection, but there are some things you need to know before purchasing one.
The Platinum Group Metals (PGMs)
There are six precious metals that are classified as platinum group metals: palladium, rhodium, ruthenium, iridium, and osmium. They share many properties with each other, including a lustrous silvery appearance, resistance to tarnish and corrosion, and high melting points.
Pure platinum is soft and unsuitable for jewelry making, so most platinum is alloyed with other metals to increase its strength and durability. These formulations are typically a combination of 90% or 95% pure platinum, with 5% or 10% alloy of a platinum group metal.
Rhodium, which is also part of the platinum group, is a very white metal that’s used in electroplating to create a gleaming white finish on jewelry. However, because rhodium is microscopically thin, it can wear off over time and must be replaced.
Another PGM, palladium is a harder and more scratch-resistant metal than platinum. It has a slightly darker hue, but it’s visually indistinguishable from platinum for a trained professional.
Ruthhenium is about fifteen times rarer than platinum, which makes it a difficult and expensive metal to use for making jewelry. Ruthenium is added to both platinum and palladium jewelry alloys in small amounts to increase their durability. Typical formulations of platinum and palladium jewelry alloys include 5% ruthenium.