Cramer: These stocks actually stumped me!

Confused man scratching head
Cameron Whitman | iStock | Getty Images Plus

Though Jim Cramer may seem to some like an infinite source of knowledge on stocks, the reality is that sometimes he doesn't know the answer and has to go back to the drawing board.

That is why he took the time to do his homework and follow up with Cramerica on a few stocks from callers that stumped him.

Real Industry
On June 23, a caller asked Cramer about Real Industry, which is a tiny company that was available only over the counter until late April. It is what is known as a Special Purpose Acquisition Company, or SPAC. Basically, it starts as a pile of money with a management team that plans to make a bunch of acquisitions.

Real Industry currently has two brands. The first is Real Alloy, a scrap aluminum business, and the second is Cosmedicine, a cosmetics maker.

The trick to looking at an SPAC is that the investor must believe in the management, because you will basically be investing in their ability to make strategic mergers and acquisitions.

"It's extremely speculative, and when you consider that Real Industry got slammed today…I say it's too risky for me," the "Mad Money" host said.

Spark Therapeutics
On June 17, a caller asked about Spark Therapeutics, a development stage biotech that is focused on gene therapy. The company was founded less than two years ago and came public in January. The stock rallied up to $80 in March from its initial pricing at $34, but then was hit alongside the rest of the biotech group.

Spark is all about developing one-time gene therapy treatments for individuals with debilitating genetic diseases. The company has enough cash to fund its operations through 2018, and Cramer found the leadership team to be impressive.

Cramer advised that this stock could be worth speculating on, especially because it pulled back 15 percent since the end of May. However, he warns investors to remember that this is a very volatile stock; there will be some pain.

Eagle Pharmaceuticals
Last Friday, a caller asked about Eagle Pharmaceuticals, and Cramer advised that he had to do more homework on it because of the monstrous move the stock had recently had. Eagle is a specialty pharma company that tries to make proprietary improvements on FDA-approved injectable drugs.

The company currently has a lot going for it, with three drugs on the market and a promising pipeline for the treatment of Chronic Lymphocytic Leukemia and Non-Hodgkin's Lymphoma. It also had a major licensing agreement with Teva earlier in the year, which triggered the stock's rally.

"I have to believe that the positives are mostly baked in. Eagle feels too rich for me. But that said, I would not be at all surprised if it catches a takeover bid sometime in the next year," Cramer said.

----------------------------------------------------------
Read more from Mad Money with Jim Cramer
Cramer Remix: These oil stocks look cheap
Cramer's pizza wars! Bringing you the dough
Cramer: Greece is the next Venezuela
----------------------------------------------------------

Lion Biotechnologies
This is a very tiny biotech stock that a caller asked about last Wednesday. The company came public in 2010, and after soaring to $165 in 2011 and crashing as low as $1 in May 2013, it has been stuck trading between $5 and $15.

Lion is a developmental stage biotech that focuses on cancer immunotherapy, which is a really hot area right now. It specifically uses special immune cells, known as tumor infiltrating lymphocytes, to attack solid tumors. That sounds really snazzy, but it is an approach that is unproven.

Cramer found this stock to be too risky for his taste; Lion has never generated any revenue as a public company, and it raises equity frequently in order to fund operations. It's one lottery ticket that Cramer isn't willing to buy, as no one will know the answer if the cancer treatment works for a very long time.

Questions for Cramer?
Call Cramer: 1-800-743-CNBC

Want to take a deep dive into Cramer's world? Hit him up!
Mad Money Twitter - Jim Cramer Twitter - Facebook - Instagram - Vine

Questions, comments, suggestions for the "Mad Money" website? madcap@cnbc.com

Cramer's New Book