Since this is HN, as an aside, Surat (the city mentioned in the article where the gems are polished) holds the dubious record of being the last major city in the world to have had an epidemic of the bubonic plague[1] back in 1994. They took the opportunity to really clean up the place after that.

Today, Surat is known for another distinction: the world's largest office building[2] (even larger than the Pentagon).

[1] https://en.wikipedia.org/wiki/1994_plague_in_India

[2] https://en.wikipedia.org/wiki/Surat_Diamond_Bourse