I made out the latin to be
MESSI TER FELICI
and it matched with what Ip said
The History and Antiquities of Somersetshire;: Being a General and ... - Volume 1, Parts 3-6 - Page 166 - Google Books Result
William Phelps - 1836 - Church history
Motto: Messi ter felici. "In memory of Lieut. Henry Lewis, R.N., who died November 16th, 1788, aged 57 years
& Thanks yes I'd agree its Carnelian
as for selling it to the family... Err Its was found in my Grandfathers davenport so I'd guess I'm a descendant
lol