Lawrence of Moravia mentions gasoline costing 60 cents a gallon. For the 1976 perspective: the median household annual income was $12,700.00; a 15 piece bucket of KFC was under $5.00; and college tuition, fees, housing, and food ran about $1,500.00 a semester.
Pearls of that size do exist. However, gem pearls are from oysters and are made of iridescent nacre; giant pearls are from giant clams and are made of dull calcareous concretion. These massive 'pearls' are lumpy, dull white and not particularly valuable.