If you've ever gotten an email or seen an online advertisement pumping the potential to get rich buying penny stocks, you're not alone. The perception that you're "getting in early" on some great growth story is very appealing.

But here's the catch: Most penny stocks that you see advertising as having generated big gains for their investors, quickly lose their value, wiping out people who fall for the scam. Furthermore, successful companies don't start off as penny stocks. Great ideas with talented leaders get funded and go public with big financial backing. Great investing ideas like Amazon.com in the late 1990s and Microsoft in the early 1980s didn't get discovered in the back of a penny-stock newsletter. 

But if you're considering penny stocks, then you're probably willing to invest in higher-risk stocks that could generate big returns for patient investors willing to ride out the ups and downs. Three Motley Fool contributors have identified NV5 Global Inc (NASDAQ:NVEE)Crispr Therapeutics AG (NASDAQ:CRSP), and Tesla Inc (NASDAQ:TSLA) as risk-reward stocks well worth considering. 

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Keep reading below to learn why you should consider these three companies before wasting a single penny on penny stocks. 

Risk-reward on this high-flying growth stock

Jason Hall (NV5 Global): If you're looking to find a "next big thing" stock, NV5 Global is worth a very close look. With sales of less than $390 million over the past 12 months and a market cap below $1 billion, this company definitely fits the bill as a small fish in the very big pond that is global infrastructure. 

But the small engineering and consulting company is growing very quickly under the leadership of founder, CEO, and biggest shareholder Dickerson Wright. Revenue is up 172% over the past year, while earnings per share has increased 157%. Wright's M.O. is heavily geared toward growth by acquisition, which can be hard to do well, but he has a long track record of success, and the engineering space is ripe for consolidation, with well over 100,000 engineering firms in North America alone. 

NVEE Chart

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Furthermore, the growth potential is enormous. Tens of trillions of dollars must be spent globally over the next several decades to modernize aging infrastructure in many developed countries, and emerging nations will add more than 1 billion new middle-class urbanites over the next decade alone. That should bode very well for NV5's prospects. 

The risk is that it's a very small company and its prospects are heavily tied to Wright remaining at the helm. But so long as he remains involved and the company continues to do well integrating its many acquisitions and paying a reasonable price to acquire them, investors should be able to make a lot of money. 

The future is here

George Budwell (Crispr Therapeutics): If you aren't put off by heavy doses of risk, you might want to check out the gene-editing pioneer Crispr Therapeutics. Although this speculative biotech stock has already doubled in value this year, top analysts at firms like Goldman Sachs think Crispr's shares remain woefully undervalued relative to the company's long-term growth potential. In fact, Goldman has the company's acquisition value listed at $148 per share, implying a staggering 202% upside potential from current levels. 

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What's got Wall Street so excited? Apart from the fact that the CRISPR gene-editing platform is widely expected to revolutionize human medicine and agriculture, Crispr, as a company, has a commanding lead over its closest rivals Editas Medicines and Intellia Therapeutics in terms of clinical development.

Crispr and its partner Vertex Pharmaceuticals, for instance, are on track to advance their gene-edited autologous hematopoietic stem cell therapy, CTX-001, into human trials for both beta thalassemia and sickle cell disease by year's end in a handful of ex-U.S. territories. Crispr and Vertex are also working on getting the clinical hold lifted on the therapy inside the United States. Crispr thus has a decent shot at becoming the first publicly traded company to actually commercialize a CRISPR-based therapeutic. 

Unfortunately, the safety and efficacy of this novel gene-editing platform remains unclear at this point. This promising technology could prove to be a seminal development in the battle against scores of deadly ailments -- but it might also prove to be too dangerous to use in human subjects on a wide-scale basis. And that's why this clinical-stage biotech stock is arguably only fit for the most aggressive of investors. 

High-risk, high-reward

Daniel Miller (Tesla): Buying penny stocks is more comparable to gambling than it is investing, but for many the allure of buying the next big thing or making it rich overnight is compelling. The thing is, investing is hard enough already without the added risk of penny-stock scams and other negatives that come with those stocks, so if you're going to take sizable risk on investments, do it with a company that actually has immense long-term potential to go along with the high-risk -- a company like Tesla.

Tesla is certainly a high-risk investment, currently. While the company has recently backed down from its consideration to go private, there are still potential lawsuits stemming from CEO Elon Musk's tweets about going private, massive cash burn, and the uncertainty surrounding what production level of the Model 3 can be sustained. On the flip side, it's easy to root for a company trying to advance the adoption of sustainable energy solutions through its vehicle and solar panel businesses -- and those businesses could one day be incredibly lucrative compared with today. 

But for Tesla to reach that potentially lucrative future, it's in a race to ramp up production of its Model 3 to prove it can become profitable. There's also reason to be optimistic about Tesla's future, as it will wholly own and operate a plant in Shanghai in a few years, and China will likely end up as Tesla's largest market down the road. Investors also had encouraging remarks from Evercore ISI analyst George Galliers, who, after taking a factory tour, noted the automaker seems close to achieving a consistent 5,000 to 6,000 weekly unit production rate and that it could get to 7,000 to 8,000 units "with very little incremental capital expenditure." 

If you're willing to take on risky penny-stock investments, it'd be wise to instead invest in a high-risk company with a visionary leader and potentially lucrative business transitioning the world to sustainable energy transportation.

John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Teresa Kersten is an employee of LinkedIn and is a member of The Motley Fool's board of directors. LinkedIn is owned by Microsoft. Daniel Miller has no position in any of the stocks mentioned. George Budwell has no position in any of the stocks mentioned. Jason Hall owns shares of Amazon, CRISPR Therapeutics, Intuitive Surgical, Netflix, NV5 Global, and Tesla. The Motley Fool owns shares of and recommends Amazon, Intuitive Surgical, Netflix, and Tesla. The Motley Fool owns shares of CRISPR Therapeutics and NV5 Global. The Motley Fool recommends Editas Medicine and Vertex Pharmaceuticals. The Motley Fool has a disclosure policy.