True penny stocks are a minefield, but the copper beauties we pick up in my weekly column "Making Cents in Penny Stocks" are often just beaten-down winners whose shares have fallen below the $10 mark.

At the other end of the spectrum lie what I call "three-digit stocks," though if they're anything like Berkshire Hathaway, they can trade in the four-, five-, and six-digit range, too. While a penny stock might not be a good buy simply because it's cheap, a three-digit stock shouldn't scare you away just because it carries a hefty price tag. We'll consult the Motley Fool CAPS community to see which of these high-priced highfliers might have the best chances of success.

For the first 20 months after we began tracking CAPS data, we found that newly minted five-star stocks offered the best opportunities for investors, while lowest-rated companies fared the worst. By pairing that information with our three-digit wonders below, we'll have at least an inkling of whether these stocks can maintain their lofty valuations.

Stock

3-Digit Price

CAPS Rating

Return on Capital, TTM

PetroChina (NYSE:PTR)

$101.25

****

13.4%^

CNOOC (NYSE:CEO)

$105.93

****

21.9%

Martin Marietta Materials (NYSE:MLM)

$102.00

**

9.5%

Source: Capital IQ, a division of Standard & Poor's. TTM = trailing 12 months.  
^ As of June 30, 2008, last report.

How do you say "oil" in Chinese?
Although coal remains China's top resource for energy production, oil continues to grow in importance. For that reason, PetroChina's announcement that China's oil imports have reached parity with domestic production is sparking some concern. Imports have doubled since 2003, while domestic sources have risen by only 11%. Some analysts think the growing imbalance may have driven China's recent decision to go after Somali pirates, in hopes of protecting future supplies.

Yet PetroChina could soon face margin pressure as well. Along with Sinopec (NYSE:SHI), the Chinese refiner is feeling the heat as Beijing cuts fuel prices for the first time in nearly two years. CAPS member brentvoss, however, figures that demand will remain high in that country, ultimately benefiting the refiners:

Oil demand will remain high in China. This is a given. China will rise to become a much bigger economic powerhouse than it is today. This is the century of China.

Offshore, on target
That same set of circumstances may end up influencing CNOOC, China's largest offshore oil explorer. Many deepwater drillers, such as Transocean (NYSE:RIG) and Atwood Oceanics (NYSE:ATW), were hurt by the precipitous drop in oil prices, which made investors think that profits might not be as refined as they once were. Yet Transocean faces other problems, like high levels of debt, while CNOOC's debt, a mere 8% of its capitalization, makes it a bit more nimble.

CAPS All-Star tutaemeia believes that all of these factors warrant a CNOOC buy:

The demand can been decreasing but when it pump again, CNOOC will rise. And by the way of the train maybe the oil price is arriving to the bottom.

My outperform bet is justify becasue CNOOC is not just a solid company but have a lots of money in cash, few debt, nice past earnings growth and a good [return on equity]. That's why i am long of this stock! Are you with me?

Aggregate aggravation
As Mexican cement giant Cemex (NYSE:CX) has shown, when industry prospects begin to unravel, one big company's woes can take down a lot of ancillary businesses. CAPS All-Star SuperPicks thinks aggregates specialist Martin Marietta Materials will also suffer until another building boom arrives:

here we are in a new economy - within a deleveraging landscape. these companies are the biggest & baddest that have beaten the S&P 500, however, upon closer look these companies valuations appear too high, future growth is constricted by debt levels, and already have pretty high institutional ownership for its size.

this stock will not double in the next 5 years...but if it does, thats bcuz most of the other stocks in your portfolio have tripled or done much better during that time frame.

Count to 10
These three-digit stocks might be on their way to even higher valuations. That's why it pays to start your own research on these stocks on Motley Fool CAPS. Read a company's financial reports, scrutinize key data and charts, and examine the comments your fellow investors have made, all from a stock's CAPS page.

Sign up today for the completely free service, and let us hear what you have to say about the great and almost-great companies that interest you.

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Cemex and CNOOC are Global Gains recommendations. Costco is an Inside Value selection. Cemex, Costco, and Atwood Oceanics are Stock Advisor selections. The Fool owns shares of Cemex.

Fool contributor Rich Duprey does not have a financial position in any of the stocks mentioned in this article. You can see his holdings here. The Motley Fool has a disclosure policy.