Based on the clue 'citrus fruits including limes were introduced to t...', what is the answer?

Based on the clue 'citrine which is cut into gemstones is a variety o...', what is the answer? What is referred to by 'citron'? Based on the clue 'citrus drink franchise owned by the conqueror of g...', what is the answer? Based on the clue 'citrus fruit named for the resemblance of its apex...', what is the answer? What is referred to by 'citrus limon'? What is referred to by 'citrus sinensis'? What is referred to by 'citta di castello rome'? Based on the clue 'city country in which the dynasty of the ptolemie...', what is the answer?