The robbery took place when Shilaben Soni, who runs the shop with her husband, was alone, police said.
Two persons, pretending to be customers, entered the shop around 1.30 pm and asked her to show some jewellery.
As she turned her back to get a box of jewellery, one of them jumped over the counter and gagged her with a piece of cloth.
Three men, apparently waiting outside, entered at this point and collected jewellery in a bag before all five of them fled.
Police commissioner Manoj Shashidhar said that CCTV footage will help police identify and track down the culprits. Probe is on.