Diamonds worth Rs 4 crore were stolen from a diamond processing unit on Charni Road on Wednesday night.
The unit is located on the fourth floor of Sakina Manzil, Charni road.
The police said the robbery came to light when an employee, Mahesh Ajmera, found about 2,800 carats of diamonds missing when he came to work on Thursday morning.
Ajmera informed the police who reached the spot, collected fingerprints, and got sniffer dogs to survey the premises.
Initial investigation revealed that the diamonds were removed from six lockers. The police are baffled because the accused had shut the lockers neatly after removing the diamonds. The door of the unit was also locked after the crime.
A senior police officer requesting anonymity said six duplicate keys could have been used to open the lockers. “Making so many duplicate keys are difficult for someone who plans to break-in,” he said.
The closed circuit television camera installed inside the unit failed to capture anything because the room was dark.
The police said the building had no watchman.
The police are questioning the employees of the unit and of other offices, and residents of the area.
“We are investigating all angles,” Deputy Commissioner of Police (zone 2), Sanjay Mohite, said.