The term 'alternative investment' can be used for anything outside the staple financial assets of shares, bonds and cash, but in its truest sense it refers to an investment that has a low correlation with these markets, and therefore offers diversification. Non-financial alternatives span a broadrange including precious metals, diamonds, antiques, coins and various other collectables among other things.
Alternatives have a number of pros and cons. On the plus side, apart from providing diversification, they may offer a great deal of enjoyment, whether through researching the subject, ownership, or even - in the case of wine - consumption along the way.
On the negative side, alternatives are not generally regulated; successful investment depends upon expert knowledge - which you may have to pay for; and investments are likely to be relatively illiquid, so they may be a lot easier to buy than to sell. And just like conventional financial investments, their value can of course go down as well as up.
It's been a torrid few years for investors in Bordeaux wine. First of all, the region had a disastrous 2013 vintage - some described it as the worst in 30 years - following two poor harvests.
That contributed to big drops in export sales to key markets such as China and the UK, and a weakening demand for investment.
The market price of leading wines bought at or before the market peak in 2011 plummeted and has shown little sign of recovery.
Even over the past 12 months, the Liv-ex investment indices - which measure the investment performance of fine wine, the vast majority of it from Bordeaux - are each down by between 6 per cent and 14 per cent, year-on-year.
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The market peak in 2011 followed a period of speculation, especially from China, that with hindsight looks like a bubble. 'Prices are down considerably and we don't see them recovering to 2011 levels any time soon,' says Aarash Ghatineh, head of sales at fine wines investment company Cult Wines.
'Some prices, particularly for the 2008 vintage, had got ridiculous, and there is an impact from the austerity measures that have been introduced by the new Chinese government, which mean people are not willing to pay so much.'
He nevertheless thinks prices will recover some of the lost ground, providing opportunity for those who get into the market now.
But there are also signs that the hegemony of the first-growth Bordeaux wines - the Margaux, Lafittes, Latours, et al - may never be quite the same again. In the past these have been regarded as the only serious investment-grade wines, but that may be changing.
Sotheby's recently broke the record for a single lot of wine with a case of the top-classed Burgundy, Domaine Romanée Conti, while outsiders such as Burgundies, 'super-Tuscans', prestige Cuvee Champagnes and some New World wines are lining up to press their credentials for investment.
Ghatineh says that the less rarified chateaux from Bordeaux - classified as second to fifth growths - also offer opportunity, and that by avoiding paying over the odds, his company's clients have largely kept their investments above water in the falling market.
Wine investing has never been so intensely scrutinised as it is now, with investment companies offering live trading platforms and price tickers, but the prospect of making easy returns looks less certain than previously.
For those seeking to invest in wine for the first time, the advice is to be very careful who you deal with. This is an area that has attracted scammers, and dozens of wine investment companies have closed in the past few years, leaving investors high and dry.
There is a Wine Investment Association (wineinvestmentassociation.org) that was formed in response to the level of fraud, which has useful information on investing safely.
Berry Brothers & Rudd, one of London's longest-established wine merchants, suggests that you should start with at least £10,000 to create an investment cellar.
The two main options are to buy wines by the case in the early years of a new vintage; or to buy en primeur - before the wine has been bottled. The latter option is less expensive but carries a much higher risk since a vintage has not been really put to the test at this stage.
Collective routes to wealth and happiness
There are a number of funds that invest in fine wine, but these are primarily aimed at institutional investors.
The Wine Investment Fund (wineinvestmentfund.com) is a limited partnership in the UK, which is open to 'sophisticated' investors, with a minimum contribution level of £10,000.
It is not regulated, and for UK investors no redemptions are allowed during the lifetime of each tranche of investment. The net asset value has fallen year-on-year for the last three years.