Platinum is a precious metal more rare and valuable than gold, but most people don’t know the basics of buying platinum jewelry. For example, there are markings that indicate the purity of genuine platinum – but what do they mean?

Since platinum is very strong and durable (much more so than gold), it is typically used in a very pure form, often as high as 95 percent. Platinum jewelry basically falls into three categories of purity, each with its own type of marking: Platinum, Plat/Pt, and platinum group metal mixtures.

Platinum

Jewelry that contains at least 95 percent platinum (or 950 parts per thousand) can be sold simply as platinum, according to the U.S. Federal Trade Commission (FTC). A piece of this jewelry will simply have the marking “platinum”.

Plat/Pt

Jewelry that is 85, 90 or 95 percent pure will be marked as “Plat” or “Pt”, with the parts per thousand in front, for example: “900Pt.” or “850Plat.”

Platinum Group Metal Mixtures

Another type of jewelry is made from a mixture of platinum and one or more metals that fall into a certain group. These are called the “platinum group metals”, and include:

A piece that contains at least 50% (500 parts per thousand) of platinum, and a total of 950 parts per thousand of any of these metals, can be marked as platinum jewelry as long as the amount of each metal is disclosed, for example: “700Plat. 200Pall. 50Irid.”

Since these metals have very similar chemical properties to platinum, these mixtures allow a jeweler to make a more affordable piece that looks brilliant and has the resistance to wear, tarnish, and chemical attack of pure platinum. They are also hypoallergenic, and so are a good alternative to white gold for people susceptible to skin allergies.