Updated from 5:31 p.m. EDT

Crystallex ( KRY owns a gigantic undeveloped mine in Venezuela, its shares have more than doubled since the year began, and its story is one that can traders can apply to all of their investments, said Jim Cramer on his "RealMoney" radio show Thursday.

This mining stock provides a fine example of the correct way to use his advice, Cramer said. Though he's a fan of the discipline of buying low and selling high, people tend to buy a stock when the price has run up, hoping it will keep going.

"Hope is not part of the equation on Jim Cramer's 'RealMoney,' he said. "We're trying to change the odds and take hope out of it."

Crystallex is fundamentally strong, he said, but the stock has been pulling back in recent days. The good news is that presents an opportunity for investors who want to play it smart, Cramer said.

"When stocks are sliding you should be interested in buying, when stocks are soaring you should be interested in selling," he said. "I have found the best way to make big, real money is to look out six to 18 months from when you first purchased a security."

Cramer admitted he, like many investors, can be impatient and in a rush to make money immediately. However, the best approach is often the opposite -- decide that you could be early and wait it out to see if your thesis materializes.

"If you do your homework, and you feel the company is strong, and you think the prospects are good, then you need to wait usually six to 18 months before anything really can happen," he said. "I was early, but I was patient."

He recommended Crystallex at $2 and nothing happened for months. Then it eventually went above $6 a share. Now, it's dropped a bit. For investors who believe in Crystallex, the pullback is a chance to buy the weakness. Should the price drop in the near future, Cramer said, it's because people are selling strength and taking profits. Meanwhile, nothing has changed at the company.

Cramer said he believes Venezuela's environmental regulators will approve the company's mine project, and because the gold is located near the surface, Crystallex will be mining gold at fraction of the cost for which it's now selling.

"As a stock gets stronger I sell a little, and then when it gets weaker I buy that stock back," he said. "It's called trading around. I have been a huge beneficiary of trading around."

He said he owed a good part of his returns while he was managing a hedge fund to the same approach.

Shifting gears away from his stock of the day, he suggested traders sell Zoltek ( ZOLT, a play on alternative energy that he first liked around $9. The stock is now above $22, and Cramer said it might be time to get out. Alternative energy might well have a future, he said, but it's decades away from being a true factor in the energy realm because of the dominance of crude oil.

An energy stock he recommends now is Cheseapake ( CHK - Get Report), a natural gas company that's fallen to around $31 from $38 as gas prices have declined.

Titanium Metals ( TIE presents an interesting situation because the stock has jumped from around $8 to above $54. A caller wanted to know if Cramer thought it was time to take some money off the table. In this case, he was reluctant to back that notion, pointing to news that the company's chairman just bought 50,000 shares.

"He bought up 500%," Cramer said. "That tells me that the stock's not done going up."

Meanwhile, in response to a caller's question, Cramer said health-care giant Johnson & Johnson ( JNJ - Get Report) might create some value in the next year and a half, but consumer-products titan Procter & Gamble ( PG - Get Report) would be the better option.

Another called asked about restaurant chain Texas Roadhouse ( TXRH - Get Report), a company Cramer said was doing everything right, but is currently underappreciated. The story, he said, is similar to one of his previous picks that took some time to come through, burger seller Sonic ( SONC.

Other companies whose prospects Cramer liked were driller Patterson-UTI ( PTEN - Get Report) and video-game seller GameStop ( GME - Get Report).

Though he said he wouldn't give up yet on Martek Biosciences ( MATK, he said the name will probably be weak as long as the broader health-care sector is sluggish.

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James J. Cramer is a director and co-founder of TheStreet.com. He contributes daily market commentary for TheStreet.com's sites and serves as an adviser to the company's CEO. Outside contributing columnists for TheStreet.com and RealMoney.com, including Cramer, may, from time to time, write about stocks in which they have a position. In such cases, appropriate disclosure is made. To see his personal portfolio and find out what trades Cramer will make before he makes them, sign up for Action Alerts PLUS. While he cannot provide personalized investment advice or recommendations, he invites you to send comments on his column by clicking here. Listen to Cramer's RealMoney Radio show on your computer; just click here. Watch Cramer on "Mad Money" at 6 p.m. ET weeknights on CNBC. Click here to order Cramer's latest book, "Real Money: Sane Investing in an Insane World," click here to get his second book, "You Got Screwed!" and click here to order Cramer's autobiography, "Confessions of a Street Addict."