What does PB PLAT mean when engraved on a ring?

[iwantsparkle]

I am trying to sell a ring setting and someone wants to know if it’s 900 or 950.

All I see inside the ring is some tiny mark I can’t make out ahead of “PB PLAT.” The tiny mark doesn’t look like a letter or number.

Anyone familiar?

 

[scarsmum]

PB is the maker. I guess it isn’t identifying the grade of platinum.

 

[iwantsparkle]

PB is the maker. I guess it isn’t identifying the grade of platinum.

Thank you!