A trial saw footage of the lead-up to the raid in Newton Mearns, Glasgow, when masked raiders armed with hammers and a machete smashed display cases.
Alan Mitchell, 34, from Cambuslang and Gary Mitchell, 20, from Shettleston, Glasgow, denied the assault and robbery in Eric N Smith's shop in Ayr Road on April 13 but a jury found them guilty. A third raider is still at large.
At the High Court in Edinburgh yesterday Alan Mitchell was jailed for eight years.
Judge Lord Jones noted that his criminal record includes using a firearm during a bank robbery.
Gary Mitchell was sentenced to six years' detention.
The trial heard that the raiders were in the shop for only 33 seconds. But during that time they caused damage estimated at more than £210,000.
Eric Smith and his wife Yvonne were threatened with a machete by one of the robbers who stood guard while the other two smashed their way into a display case with hammers.
Defence QC Gordon Jackson said Alan Mitchell, who did not give evidence at the trial, was maintaining his silence and his denial that he had participated in the raid.
Solicitor advocate John Carroll, for Gary Mitchell, said he had been trying to turn his life around.
"It is clear that those efforts have been fruitless," said Lord Jones.