The number of 12.5kg gold bars being bought by wealthy customers has increased 243pc so far this year, when compared to the same period last year, said Rob Halliday-Stein founder of BullionByPost.
“These gold bars are usually stored in the vaults of central banks and are the same ones you see in the film ‘The Italian Job’,” added David Cousins, bullion executive from London based ATS Bullion.
The bars which are made from pure gold and are worth more than £300,000 each at today’s prices of $1,223 (£760) an ounce.
Mr Cousins added that he has seen more confidence from gold buyers this year as prices remain stable after sharp falls in the price of gold last year.
The sales of 1kg gold bars, worth about £25,000 each, has doubled during the three months ended August, when compared to the same period last year, according to ATS Bullion sales figures.
Sales of the more popular gold coins such as the quarter ounce sovereign and one ounce Krugerrand have also doubled this year, according to figures from BullionByPost.
Mr Halliday-Stein said that while most customers arrange for secure storage of the larger bars in secret vaults operated by Brinks, some customers have taken physical delivery of the 12.5kg bars. The small coins can also be sent in the post.
As the independence vote takes place, Scottish investment in physical gold has surged by 42pc in the past fortnight – on top of the traditional rise in gold demand at this time of the year.
The figure, which comes from, the world’s biggest online platform for private investors who want to trade physical gold and silver, suggests that anxious Scotland-based investors are turning to gold as a means of insuring against the uncertainties posed by a Yes vote in Thursday’s referendum.
Bullionvault analysed customer data over the year, stripping out those of 50,000 customers who lived in the UK and then dividing this group further into postcodes north and south of the border.
It then averaged the proportion of transactions typically undertaken by Scotland-based traders out of the whole of the UK over the past year. That figure was then compared to the proportion of Scottish transactions undertaken in the first half of September.