Investment scam victims are losing £20,000 on average to frauds which may involve fake diamonds, bogus stocks and shares and fine wines that do not really exist, Citizens Advice is warning.
In one case seen by the advice charity, a man paid £150,000 for diamonds that turned out to be worth a fraction of the cost.
Analysis of 5,000 scams reported to the charity between January and March 2016 showed how fraudsters are conning savers and investors out of tens of thousands of pounds.
Citizens Advice warned people are being duped by promises of strong returns by cold calls, online adverts and fake websites.
But the return on their investment fails to materialise and investors are unable to contact the trader.
Pensions are also being targeted, with offers of "free" advice on how to increase investments.
The pension freedoms launched in 2015 give the over-55s much greater choice over how they use their pension pots - but this has also sparked fears that fraudsters will see these people's savings pots as a particular target.
Citizens Advice and the Chartered Trading Standards Institute have launched Scams Awareness Month - a national campaign to help people avoid falling prey to scams.
The campaign urges people to take three steps to avoid being ripped off - get advice, report it and tell others about it.
Scammers use various tactics to trick people into parting with their cash, with people losing an average of £2,500 across all types of scam, Citizens Advice said.
Methods include vishing - whereby scammers cold-call people in a bid to get their bank details, and offers of fake services, such as telling people their computer has a virus that they can fix remotely.
While investment scams tend to be less common, they are by far the most costly, with an average loss of £20,000.
People are persuaded to invest in diamonds and gold that do not exist or are not the product that was offered.
Among the investment scams looked at by Citizens Advice, a man paid £150,000 for diamonds which although genuine, turned out to be worth a fraction of the cost.
People are also being persuaded to buy vintage wines with promises that their value would increase over time.
One person invested £500 after being offered a steep increase and cash back from the trader. The money never arrived, and when they tried to cancel they were unable to contact the trader.
Looking at scams involving stocks and shares, Citizens Advice said one person invested £65,000 with a share trader who offered them 3 per cent in dividends every month. They contacted Citizens Advice after the trader made excuses not to give the money back.
Gillian Guy, chief executive of Citizens Advice, said: "Scams can devastate people's finances and leave them empty handed.
"Fraudsters vary their tactics to target different people, from pushing cut-price offers to those on a budget, to high-interest investments for those looking to grow their savings.
"We're warning people to be on their guard against opportunities that come of the blue and far exceed the deals you'd get elsewhere - they may well be a scam.
"If you think you've lost money to a scam, seek advice as soon as possible so you have the best chance of getting your money back. It's vital that people who have fallen prey to fraudsters alert others to stop the scam from spreading, and report it to the authorities so we can stop con artists from getting away with it."
Leon Livermore, chief executive of the Chartered Trading Standards Institute, said: "Anyone can fall victim to a scam and while the criminals' methods are becoming increasingly more sophisticated, the advice remains the same, if it looks too good to be true, it probably is."
A Department for Work and Pensions spokesman said: "Anyone over 50 can get free and impartial advice on their defined contribution pension through Pension Wise and if you think you've been a victim of a scam, contact Action Fraud."