What are these stamps on inside ring?

Ive had this ring for many years just stored away in my drawer, was given to me by a family member years ago.

Can someone explain the stamps to me inside the ring , as I cant understand what they mean?I've zoomed in as much as I can. I thought it said 18 ct for the gold but after zooming in I notice it has a dot in it? It then has 22 on the other side. I'm confused lol. Thankyou very much! :)

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Dana ♥

The Centenary Diamond
my guess is that the white part of the ring is platinum, and the yellow part is 18kt gold.

my first thought was that it said Plat 1.8ct, because sometimes diamond rings have the weight of the diamond included on the stamp - but the center stone looks closer to 6mm.

no idea about the 2 2, though.
The marks stamped inside the rings serve to describe the basic properties of a piece of jewelry, usually, this information includes the Type of metal. The purity level of the metal. Carat weight of the diamond