What we as investors witnessed from cryptocurrencies last year is something that may not be duplicated again. A single asset class gained more than 3,300% in market cap (almost $600 billion) over a span of just 12 months. It's essentially a lifetime's worth of gains for some investors that were crammed into only one year.

Of course, 2018 hasn't had nearly the same flair as 2017. After beginning January on a high note, cryptocurrencies fell off a cliff, losing 67% of their market cap, from peak to trough, between Jan. 7 and Feb. 6. Everything from the prospect of increased regulations in South Korea to Facebook banning cryptocurrency advertisements hit the market hard.

View photos A rising green chart in front of digital price quotes for Litecoin, bitcoin, and Ripple. More

Image source: Getty Images.

Then again, some aggressive investors saw the drop as a buying opportunity. In the two weeks following Feb. 6, digital currency valuations again doubled. This whipsaw action has become commonplace for a market that's predominantly driven by emotionally charged retail investors.

Take note: These virtual currencies could still double

Yet even with a plethora of risks and the volatility, a handful of virtual currencies continue to stand out thanks to their proprietary blockchain technology -- the digital, distributed, and decentralized ledger that's responsible for logging all transactions. While guessing the next move in virtual currencies has proved to be more of a crapshoot than Wall Street typically prefers, the following three cryptocurrencies may have a genuine shot at doubling from their current market caps.

1. Ethereum

Feel free to call me nuts, but I believe the second-largest cryptocurrency by market cap has the potential to double and/or surpass bitcoin in total value. In fact, I've been of the opinion for quite some time that Ethereum deserves to be the most valuable cryptocurrency in the world, by market cap.

Ethereum's selling points are its blockchain and enterprise clients. Its blockchain has three very distinct differences from bitcoin that should allow it to close the market-cap gap with the world's largest cryptocurrency. First, Ethereum can process almost three times as many transactions per second as bitcoin can. Not only are these transactions processed more quickly, but they're considerably cheaper, with the average transaction on the Ethereum network costing less than $1, and the average bitcoin transaction cost pushing north of $28.

View photos Messy piles of physical silver and gold Ethereum coins. More

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