In April, I went out on a limb to suggest investors buy two particular small-cap stocks before they rebounded.

The first was InvenSense (NYSE:INVN), a motion-sensor specialist that was trading around 45% off its 52-week-highs after a number of uninspiring earnings reports, and downgrades over the previous year. Even so, I noted, the company still maintained strong free cash flow, a flawless balance sheet, and was trading at just 13 times forward earnings estimates.

The second was robotic surgery up-and-comer MAKO Surgical (NASDAQ: MAKO), which had plummeted 74% below its own 52-week-high after the company twice missed earnings estimates, reducing system sales guidance each time. Still, I was sure the worst was over, and the best yet to come for MAKO -- if only they could just turn in a decent quarter to prove to investors they were still on the right track.

Sure enough, both companies did just that in May, and while MAKO's report gave it a good start by meeting investors' expectations, InvenSense knocked it out of the ballpark by crushing analysts' estimates. So far, anyway, both of those small-cap stocks have managed to outperform the S&P 500 since then:

small cap stocks, INVN Total Return Price Chart

INVN Total Return Price data by YCharts

While I believe MAKO and InvenSense still have room to run, here are two more beaten-down small cap stocks that I think investors would be smart to buy before they revisit their previous highs:

CompanyMarket Cap% Below 52-Week-HighRecent PriceCAPS Rating
(out of five)
 GT Advanced Technologies  (OTC:GTATQ) $490 million 42% $4.10 ****
 LeapFrog (UNKNOWN:LF.DL) $657 million 22% $9.66 *****

Source: Motley Fool CAPS

Of solar and sapphire
First up, shares of GT Advanced Technologies stand 42% below their 52-week-high set last September, and that includes a 15% pop after analysts at Cannacord upgraded the stock on Thursday.

Even still, remember this company's fall from grace actually extends even further to the peaks hit during the middle of 2011, from which it currently sits a staggering 75% lower.

So what happened? In short, the solar equipment specialist's core photovoltaic (PV) furnace business went from boom to bust as the solar market crashed, and management has bluntly told frustrated investors that poor PV market conditions are expected to persist at least through sometime in 2014.

In the meantime, GTAT has been busy not only cutting slack from its bloated backlog, but also diversifying its operations by venturing into the sapphire market to rival, among other solutions, Corning's popular Gorilla Glass product.

What's more, as liquidity loosens with the gradually improving solar markets, GTAT's innovative new HiCz equipment promises to give solar customers an edge by decreasing the cost, and increasing overall efficiency, of solar cells going forward. When signs even begin to show that's happening, then GTAT could turn out to be one small-cap stock you certainly won't regret buying now.

A leap of (educational) faith
Next, at 22% below their own 52-week high, the shares of educational toy-maker LeapFrog should prove another great small-cap stock to buy now.

Remember, as fellow Fool Blake Bos pointed out recently, LeapFrog absolutely dominates its niche -- at least considering it holds the majority of top products in Amazon's website sections for Kids' Electronic Learning, Kids' Software and Books, and Kid's Electronic Accessories sections -- and that's no small task considering there's plenty of competition for educational electronics these days.

In addition, last quarter's earnings report from LeapFrog marked the 12th consecutive time the company has exceeded analysts' profit estimates. An,d while the first quarter is generally a very small percentage of LeapFrog's overall business, I'm convinced that the rest of this years' upcoming results will prove no different, showing just how well LeapFrog is really doing. 

What's more, remember that around 29% of LeapFrog's entire market capitalization is currently held in its $189.7 million cash horde, and the stock trades at a reasonable 13 times next year's earnings estimates. Back out all that cash, and the multiple drops to just 9.3.

Foolish final thoughts
Though both GTAT and LeapFrog are sitting significantly below their recent highs, I'm convinced these pullbacks are only temporary blips in their long-term stories. As a result, I think patient investors will be more than happy with their long-term gains if they buy these two small cap stocks today.