Platinum is a precious metal that looks similar to white gold. It is over 30 times rarer than gold but, at current prices, only commands about twice the price of gold. Platinum’s
workability is third to that of gold and silver . Platinum is resistant to corrosion. Platinum, like gold, is hypoallergenic.
Platinum jewelry is usually mixed with six other related metals: platinum, palladium, iridium, rhodium, ruthenium and osmium. But sometimes it is also mixed with copper and titanium. The platinum used in jewelry is usually 90% and more in purity, meaning that platinum makes up 900 out of 1000 parts of the metal. The purity grade is expressed as 900Plat, Pt900, or 900Pt.
It is highly suggested that you not get a platinum engagement ring with less than 90% platinum because the alloys may change the color of the platinum or reduce its durability.
Metals for Engagement Rings