Claddagh is neither 'off' the Irish coast (pace climate change, eeek) nor just outside the city of Galway. It's right in the centre of the city, opposite the Spanish Arch.

The business of putting jewels in the Claddagh ring was never seen, to my knowledge, anyway, until the 1970s or so - the rings were always gold or silver.

Here are
some pictures of the Claddagh.