None of the stolen items has been recovered.
Richard Tobin, 45, binged on two bottles of vodka before snatching the items from Christie's King Street on December 7 last year.
Tobin took a £125,000 Fabergé jewelled gold clock made in St Petersburg in 1899 and one of the maker's famous flower still lives, a silver gilt and rock crystal study of jasmine blossom.
He also stole an aquamarine necklace and hardstone animal carvings made by the court jewellers of Imperial Russia. Christie's had held a sale of Russian art the previous month.
Tobin had broken into the offices of credit asset managers Muzinich & Co in Mayfair, two nights earlier, taking a rucksack and headphones.
The Glaswegian, of no fixed address, was sentenced at Southwark Crown Court on April 8. He had admitted two counts of burglary at an earlier hearing, appearing at court via videolink from HMP Wandsworth.
Jack Talbot, for Tobin, said: "He accepts he took the items. It may be that I put before the court that he wasn't aware of the value, but that is an entirely different matter."
In the earlier hearing Judge Owen Davies QC warned Tobin he was facing a long prison sentence. He added: "What has happened to the property will be uppermost in the court's mind - as to whether it has been recovered."