Private investors grew marginally more bullish about gold in September as against August, reflecting concerns about central banks continuing to print money, according to a new barometer of opinion launched this week. But the index, however, suggests that some of the most aggressive gold bullishness has waned in recent months.

The Gold Investor Index, compiled from clients of the online gold and silver exchange, BullionVault, had a reading of 52.5 last month, up from 52.1 in August. (A reading above 50 indicates there are more buyers than sellers, and the converse is the case below 50.)

June's reading at the end of the second-quarter was 54.8. Last September, the index hit its highest level in the series to date at 71.7, BullionVault said.

The barometer of investor sentiment was launched this week at the London offices of Augmentum Capital – the technology private-equity fund whose main investor is RIT Capital Partners, and which is a shareholder in BullionVault. (BullionVault oversees about £1.1 billion (about $1.8 billion) of physical gold.)

Dollar gold prices rose to new seven-month highs during September, ending 7.7 per cent higher at a 7-month high of $1,766 per ounce. Gold priced in euros hit a new record of €1,377 per ounce, up 5.0 per cent for the month.

"The Gold Investor Index shows encouraging developments in September, particularly given these results include the announcement of QE3 by the US Federal Reserve, which has since helped drive the gold price to its current levels,” Marcus Grubb, managing director, investment, at the World Gold Council, said in a statement. The WGC invests in BullionVault.