As an investor, time is on your side. If you wait long enough, many stocks will deliver gains of 100% or more. Based on the stock market's long-term track record, you'd only have to wait around seven years for your initial investment to double.

But there are some stocks you can buy that don't require nearly that long of a wait. They're in the right industry at the right time to skyrocket. Here are three unstoppable stocks that could double your money relatively quickly.

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1. Cresco Labs

In case you didn't know, marijuana stocks are sizzling hot right now. Cresco Labs (OTC:CRLBF) is no exception. Shares of the U.S.-based cannabis operator jumped 44% last year and have risen more than 20% so far in 2021. I think Cresco's momentum is just getting started.

Cresco currently operates in nine states that together make up roughly 60% of the addressable U.S. marijuana market. These states include California, the biggest legal cannabis market in the country, where Cresco runs a top wholesale marijuana distribution business. They also include Illinois, Cresco's home state, where the company operates 10 retail cannabis stores -- half of its nationwide total.

The company's current markets aren't close to reaching their peak. And new opportunities are on the way. Arizona and New Jersey residents voted in November to legalize recreational marijuana. New York could be on track to follow suit this year. With the potential for federal cannabis reform on the way, the U.S. marijuana industry will almost certainly remain hot. 

In its latest quarter, Cresco ranked third among U.S. multistate cannabis operators based on revenue. Its market cap, though, is less than half the size of the No. 2 company. My view is that Cresco will be a huge winner in 2021 and could even double investors' money before the end of the year.

2. Fiverr International

Fiverr International (NYSE:FVRR) stock more than doubled by early May last year. By the end of 2020, shares of the freelance services platform had skyrocketed 730%. Will Fiverr slow down in the new year? I don't think so.

The company focuses on providing a largely frictionless way for freelancers and businesses needing digital services to connect. Many freelancers like that no negotiations are required as they are on other platforms. Businesses like the transparency that Fiverr offers -- they know what they'll get for their money. Fiverr calls its approach a "service-as-a-product" model, where it's as easy to buy and sell digital services as it is to purchase a product on

Fiverr expects to report full-year 2020 revenue of around $187 million. That's only a sliver of the total addressable U.S. market of $115 billion. And the company isn't limiting itself only to the U.S. It continues to expand its geographical footprint.

Despite its fantastic growth, Fiverr's market cap is still below $10 billion. With more people working from home than ever before (and more likely to consider freelancing as a result), I expect the company's platform will see rapidly increasing adoption over the next few years. My take is that Fiverr has a very good shot at doubling in the not-too-distant future.

3. Guardant Health

Guardant Health (NASDAQ:GH) was another solid winner in 2020. Shares of the self-described "precision oncology company" jumped 65%. I predict even brighter days are ahead for Guardant Health.

So what, exactly, is a "precision oncology company"? Guardant Health develops liquid biopsy products that analyze DNA fragments broken off from tumor cells. It already has two products on the market. Guardant360 helps match cancer patients with the appropriate therapy. GuardantOMNI helps drugmakers find patients with the right genomic profiles to include in clinical studies evaluating experimental cancer drugs. 

These products, particularly Guardant360, have proven to be enormously popular. Guardant Health's sales have quadrupled over the last three years and should top $280 million for 2020. But that's just scratching the surface for the company's current products. Guardant Health estimates the total U.S. market for Guardant360 and GuardantOMNI is roughly $6 billion.

Even better, the company thinks that using liquid biopsy products for recurrence cancer monitoring and early cancer detection could open up a U.S. market of more than $70 billion. Guardant Health is launching GuardantReveal in the first quarter of this year, the first blood-only liquid biopsy for residual cancer detection and recurrence monitoring. It also expects to complete enrollment in a study for a liquid biopsy targeting early cancer detection in 2021. I'm optimistic that this is another stock destined to double or more within the next couple of years.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.