The Royal Cross of King Charles II....
This ring was given to Black when he was given commission of the HMS Royal Oak, his very first Command. As he and the King were old friends, the ring was a gift of Gratitude and Thanks. You see, several years
before, Black had saved the King's life. The HMS Parliament was transporting his Majesty from New Castle down the English Channel. Just before making port in Canterbury, the "Parliament" was attacked by a Dutch Man of War. Many English Sailors and Marines lost their lives that day and King Charles would've been just another casualty had it not been for the quick action of Lt Black who, just before the English Ship's hull was splintered by Dutch cannon fire, grabbed the King by his collar and dove over the side with him. He was able to swim them both to the English side of the channel with minimal injury.
Captain Black, being a rather Superstitious man, considers the Ring to be a valuable Good Luck Charm. And as such, insists that his crew (after a full year of service) also wear the Cross... especially during times of Battle. You will see that the Valhalla's crew can also be a 'superstitious' lot as they also wear the ring often. so when you see the Captain and 'is crew there and about, Tip yer Hat, Hoist yer drink, and wish them well... as they shall you!