You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For consistency, answers should be in all lower cased letters.

Category: JEWELRY 
Clue: An engraved gem with a design that projects from the surface, it can be carved from onyx, agate or sardonyx
a cameo

Category: WATCHMAKER, WATCHMAKER 
Clue: In 1924 England's John Harwood patented a watch that could do this to itself thanks to an internal swinging weight
wind itself

Category: "E" MALE 
Clue: Around 1000 A.D. he named the North American coast Vinland

leif ericson