Gold traders in North East Lincolnshire have been losing out because their weighing scales were not measuring accurately, it has emerged.
Visits made by trading standards officers revealed inaccurate scales were working in favour of the customer.
Of 18 gold traders visited, eight were found to be using inappropriate scales. The visits were carried out to ensure fair practice within the trade.
The price of gold has reached new records over the past few months.
As a result companies that exchange people's gold for cash have grown in popularity.
Trading standards officers at North East Lincolnshire Council visited 16 jewellers and two second-hand shops.
Of the firms visited, 11 bought or sold gold by weight on the premises.
Just two traders were found to be operating in accordance with all the rules.
Councillor Steve Beasant, portfolio holder for community safety, neighbourhoods and customer services, said: "Discovering that some traders were not using the correct scales for weighing second-hand gold has allowed us to give them guidance to ensure they give a fair service to customers - and it has helped the traders, too.
"We hope this also helps to inform people wanting to sell their gold items.
"There are plenty of companies out there offering cash for gold, particularly over the internet, so it is important that consumers know what they can expect in terms of a fair deal."