The diamond industry of Surat works on trust and a close-knit community, a study by a post-doctoral fellow at Cept University says.

The study, titled "Emergence of informal sector firms in international business" and authored by Indu Rao, cited the fact that both rough and polished diamonds worth "millions of dollars" were transported by couriers with "virtually no security."

The diamond couriers "could be carrying packets in their pockets and travelling in the economy class of a train," Rao reported. "Despite opportunity, there appears to be little to no theft or heists because of the mere thought of being ousted from the community," the study concludes.

Despite Rao's conclusions, two incidents of diamond robberies took place in Surat on the same day last week. In one, a courier travelling by himself was allegedly accosted by two men who reportedly beat him and took the money he was carrying. Passers-by came to the courier's rescue and nabbed the suspects, who were handed over to police.

In another incident, a new employee of a laser unit is suspected of drugging three colleagues – including the firm's owner – and escaping with 457 carats of diamonds and three cellular phones. Police were in search of the suspect.