Anne Jones, 44, and her student son Connor, 20, told a court she saw three men with their faces masked run into Eric N Smith Jewellery in Ayr Road, Newton Mearns at 2.30pm on April 13.
Mrs Jones said she saw the glass being smashed in the shop.
She told prosecutor Sheena Fraser that about 30 seconds later she saw the same men run out the shop and into a blue Peugeot car parked in Eaglesham Road.
She said: "I waited till they passed my car and then I followed them. I didn't know what the road was so I put my satnav on and discovered it was Eaglesham Road.
"After the first bend in the road I could still see them, after the second bend I couldn't see them at all. I lost them."
She was giving evidence at the trial of Alan Mitchell, 34, and Gary Mitchell, 20, who deny robbing the jewellery shop of a quantity of watches on April 13. They have lodged special defences of alibi.
She added: "I saw three men coming round the corner with their faces masked and one was carrying an object that looked like a concrete lintel on his shoulder. I knew something wrong was happening."
Meanwhile, a doctor told how he saw three men getting out of a blue Peugeot car in Shawhill Crescent, Newton Mearns and transferring into a blue Mazda.
Dr John Robertson, 57, said that one of the men went into the boot of the Mazda and the other two got inside the car and they drove off at speed.
He said his attention had been drawn to the incident because he heard a loud bang when the Peugeot hit the pavement and one of its tyres burst.
The trial before judge Lord Jones continues.