The Star of India is a 563.35-carat (112.67 g) star sapphire, one of the largest such gems in the world. It is almost flawless and is unusual in that it has stars on both sides of the stone. The greyish blue gem was mined in Sri Lanka and is housed in the American Museum of Natural History in New York City.

Source: http://en.wikipedia.org/wiki/Star_of_India_(gem)