Auctions of collectors' items have had bumper years recently, according to The World Wealth Report by Cap Gemini Ernst & Young and Merrill Lynch, which surveys the investments of millionaires or high net worth individuals.

'Across the globe in 2002, auction houses saw increased interest and sales in art and wine collections as attractive investment options,' according to the report.

'A wine index, compiled by Fine Wine Management, outperformed equities by 97 per cent in the 2000-2002 period,' it added.

Although that three-year period was hardly the equity markets' finest hour for investors and sets a rather low benchmark for comparison, such high returns are still impressive.

The report found the millionaires on average invested 10 per cent of their wealth in alternative investments, which included luxury valuables, collectors' items and precious metals. Those who could afford to take more risks with their money tended to have more alternative investments.

'The higher the wealth band the greater the proportion of alternative investment products in the portfolio,' the report notes.

Locally, financial advisers and private banks have also seen clients edging away from the more traditional staples of equities and bonds.

'In Hong Kong ... we have clients who collect Chinese art objects such as antique jade for investment. With the changing lifestyle and increasing sophistication, our clients are acquiring expensive yachts, vintage wines, rare pens and cigars,' said Kenneth Lee, head of wealth management services at BNP Paribas Private Bank in Hong Kong.

'Initially, clients acquire these assets to flaunt their wealth but they are becoming quite knowledgeable in their value as investments, especially in the markets for assets such as wine and cigars.'

Towry Law associate director Chris Beale said some of his clients had taken to heart the importance of having liquid assets in uncertain times.

'I have plenty of clients who have bought into bars over the last couple of years,' said Mr Beale.

'Their rationale is that in these troubled times at least you've got real people buying real beer in a real bar - as opposed to buying into a fund where the price is entirely notional.'

Other clients have headed offshore for their alternative investments, only to see them sink.

'I've got a lot of clients who have bought boats and they universally say you might as well get your cash and chuck it in the harbour,' said Mr Beale.

However, buying a boat, as with many offbeat investments, can be as much to do with pursuing a hobby as the quest for a good return. 'But it is a labour of love ... and they say that accepting the fact that they are buying into the lifestyle,' said Mr Beale.

Antiques can hold their value as well as being an area of interest. Chinese antiques have the potential to increase in value as the mainland's economy develops and enables more people to buy collectors' items, thereby pushing up the price.

'As you get more affluent mainland Chinese, the market for [antiques] will develop,' said South China Brokerage vice-chairman Howard Gorges.

However, buying art and antiques can be risky. There are always questions concerning the authenticity of a painting or artefact, which requires a high level of expertise to assess. The value can change dramatically according to the prevailing tastes and fashions, which often makes buying antiques riskier than stocks.

'It is illiquid and the spread is pretty wide, unlike shares where you usually have a narrow spread and liquidity,' said Mr Gorges.

Consequently BNP Paribas recommends avoiding contemporary art, which is more likely to suffer losses from changing tastes and fashions.

'Why no contemporary art? It is true that significant investment gains can be made in this area but this is the exception rather than the rule. In a market that has a good deal to do with fashion, pieces that are expensive and in demand now can easily be worth next to nothing in 10 years' time,' BNP Paribas said in a recent report.

Investors should not see art purchases as a short-term investment and be prepared to hold a painting for the long haul. 'The investor is best advised to view art as a medium-to long-term prospect - 10-15 years minimum - and should have sufficient flexibility to stay in the market until the right moment to sell has arrived,' BNP Paribas said.

However, you do not have to be a millionaire to invest in riskier unconventional assets - there are still a few possibilities coming on the market for smaller investors wishing to spice up the conventional mix of stocks and bonds. Mr Beale puts mainland stocks into this category for Hong Kong residents, due to the riskier nature of investing across the border.

'If you look at what Joe Public might buy into ... a lot of locals buy mainland stocks where there is a far greater rollercoaster ride, greater risk attached to it and equally greater upside potential,' said Mr Beale.

Overseas there have also been some novel investment ideas. In May, the first brothel to ever go public listed on the Australian stock exchange. The Daily Planet touted its business as recession-proof and the stock quickly soared to more than triple its offer price of A$0.50 (about HK$2.66). The stock has slumped since then but initial investors are still in the money with the stock trading around 80 to 90 Australian cents.

In Britain, a Formula One racing driver sold shares in himself earlier this year. The public was invited to buy shares in Justin Wilson's future earnings - the capital from the #1.2 million (about HK$15.52 million) offering will be used to finance the start of his Formula One racing career. Investors are entitled to 10 per cent of Mr Wilson's earnings until 2012.

So what is the maximum amount of a portfolio that should be put towards such unconventional investments?

'There's no set benchmark as such - going beyond 10 per cent would make me feel a little bit uncomfortable,' said Mr Beale, although he acknowledged that some people justify putting more money into unconventional instruments as they are furthering a personal interest. 'It is a very personal thing and the higher up the food chain you go the more personal it becomes,' he said.

BNP Paribas recommends no more than 5 per cent be invested in art, with investors sticking to works of the highest quality in a bid to ensure the painting holds its value and can be resold.

'The bank recommends that our clients invest up to about 5 per cent of their portfolio in good quality art as a long-term investment. We suggest that our clients be highly selective in choosing art pieces and to avoid speculation,' Mr Lee said.