TORONTO (Reuters) - A 13 percent rise in a stock in about 10 days would normally tell investors it's time to take money off the table and wait for a chance to buy low.

Not so for the recent surge in gold equities: many see the big move up as the start of a more sustained rally.

Gold stocks, as measured by the S&P/TSX global gold index , have taken off in the early days of September, hitting their highest levels since last July, thanks largely to bullion's charge back up to the $1,000 mark.

Rather than predicting a retrench, analysts and investors are looking at favorable equity valuations, seasonal gold buying trends, and the prospect of upward earnings revisions as reasons to expect further gains.

"I wouldn't take money off the table. I'd be more of a buyer than a seller," said Ian Nakamoto of Toronto's MacDougall, MacDougall, and MacTier.

Even if gold prices trade sideways or decline a little bit, Nakamoto sees value in gold stocks that have largely lagged bullion's rise of nearly 140 percent since early 2005.

"I show them to be quite a bit undervalued," he said.

RBC Capital markets, in a note last week, said top-tier gold companies — a group that includes Barrick Gold, Goldcorp, Kinross Gold and Yamana Gold — appear to be trading at a level consistent with a long-term gold price of $865 an ounce.

The long-standing view is that gold equities should outperform the metal when it rises, as the miners' relatively fixed costs give them added leverage from a rising top line.

Soaring costs for oil, equipment and labour in recent years have reversed that relationship, leading to an equity sector that has stagnated at times, even as gold hit fresh highs.

But the retreat of oil prices from last year's peaks, along with easing inflation or outright price decreases on equipment, labor and other inputs due to the slower economy, have stoked optimism that cost inflation is coming under control.

"Fuel costs are still well below what they were in 2008, so that should help margins, and we've had some relief in terms of labor issues and ... capital costs," said Brian Hicks, who co-manages a resources fund at US Global Investors.

But for any extended rally in the sector, gold needs to build on its recent gains. Gold finished the week just above $1,000 an ounce.