Platinum rings are usually marked with a stamp that indicates the purity of the metal. The most common markings are:

* PLAT or PT: This indicates that the ring is made of pure platinum.

* PLAT 950 or PT950: This indicates that the ring is made of 95% platinum and 5% other metals.

* PLAT 900 or PT900: This indicates that the ring is made of 90% platinum and 10% other metals.

The stamp may also include the manufacturer's mark or logo.