The incident took place near Lakshmibai College when the vehicle carrying the jewellery stopped at a red signal.
A police official said that a few traders were using the vehicle to transport the jewellery from Sarai Rohilla in central Delhi.
According to reports, two men arrived on a two-wheeler and broke the window of the vehicle using a slingshot.
They grabbed a bag full of jewellery and fled.
The police have launched a detailed probe to nab the miscreants.