The advertising watchdog has banned ads for five gold dealers for failing to make clear that the investments are unregulated and their value could vary.

The Advertising Standards Authority (ASA) investigated the ads for Bullion Club, Gold Bank, Harrington & Byrne, Solomon Global and The Pure Gold Company as part of wider work on unregulated investments.

The Google ad for Bullion Club, seen in June, said “gold has historically held its value over time, making it a good hedge against inflation,” while a press ad for Gold Bank in May read: “Could this be the best investment you ever made?”

The ASA investigated whether ads for all five dealers were misleading because they failed to illustrate the risks of the investments.

The Bullion Club said they understood the importance of informing potential investors that investments could vary, and said they had amended their information to make it more prominent.

Harrington & Byrne said their ad had nothing to do with investment, and they did not state that gold was an investment vehicle or should be bought as an investment.

The Pure Gold Company said their service differed from most of their competitors in that they they did not sell products directly from their website, which acted instead as an educational tool.

The ASA said the gold investment market was not regulated in the UK, and was not subject to any protection from the Financial Services Compensation Scheme or the Financial Ombudsman Service.

The ASA said: “Because the ads did not include any risk warnings to make clear that the investments could go down as well as up, and that gold investment was an unregulated activity, and the landing page did not present that information immediately to consumers, we concluded that the ads were misleading.”

The ASA ruled that the ads must not appear again, adding: “We told The Pure Gold Company to ensure that future marketing made sufficiently clear that gold investment was unregulated, and that the value of investments was variable and could go down as well as up.”

The ASA similarly banned the ads from Harrington and Byrne, Gold Bank, the Bullion Club and Solomon Global.