Wikipedia: Abul Muzaffar Muhi-ud-Din Mohammad Aurangzeb, (1618 - 1707) commonly known as Aurangzeb and by his imperial title Alamgir ('world-seizer or universe-seizer'), was the sixth Mughal Emperor and ruled over most of the Indian subcontinent.
Silver coins from Aurangzeb were found in 1961 at the Great Basses reef off the south east coast of Sri Lanka by Arthur C. Clarke and Mike Wilson. George probably has one of these coins.
CoinQuest believes that Indian and Chinese coins will soon draw much excitement in numismatic (coin collecting) circles, and it is difficult to assign values with any certainty. The Standard Catalog of World Coins lists many variations of this coin, all with similar values. Comparing Standard Catalog values with actual auction results, we have compiled these catalog values:
1/2 RUPEE (about 20 mm diameter, about 5.5 grams)
worn: $20 US dollars approximate catalog value
average circulated: $100
well preserved: $180
RUPEE (about 24 mm diameter, about 10 grams)
worn: $10 US dollars approximate catalog value
average circulated: $50
well preserved: $80
George's coin, however, has severe problems. Perhaps the dark streaks happened when the coin was cleaned from the shipwreck. Perhaps they are remnants of jewelry mounts. In any case, they bring the value of the coin down drastically.