A Sydney jewellery store was all but cleared in just over three minutes when masked thieves broke into the shop in the early hours of this morning.

About 3am three men wielding a baseball bat and hammers smashed their way into Germani Jewellery on George Street.

In a matter of minutes, the trio - dressed in dark clothing - shattered glass display cabinets and snatched earrings, necklaces and rings before escaping in a stolen car.

Three masked men broke into a Sydney jewellery store this morning. (9News)

Store owner Michael Germani. (9News)

Store owner Michael Germani said this has been the most brazen robbery he has seen in 30 years.

"And they brought the big laundry bag. It's like a huge bag. It's like jewellery is only small items what do you need such a huge bag for?" he told 9News.

NSW Police Inspector Gary Coffey. (9News)

NSW Police Inspector Gary Coffey said the stolen car used to escape was taken from a property in Bronte in January of this year.