The Jerusalem stone was installed, and blessed, in the nave sanctuary platform of St Paul's Cathedral during the coronavirus pandemic of 2020. The original stone has an interesting history which can be read here.
The inscription, from Psalm 103.4, translates as
"He crowns you with loving kindness and tender mercies".
This reproduction of the Jerusalem Stone is available with the choice of either a brooch, or a medal on a cord. Both are approximately 33mm across.