A nearly unbreakable sapphire screen could be the make-or-break feature on Apple's newest iPhone, according to a recent survey conducted by used smartphone marketplace uSell.com.

The survey asked 1,000 U.S. smartphone users to rank the features they wanted to see most in Apple's next iPhone, which is widely expected to be unveiled in September. More than 45 percent of respondents listed a scratch-resistant sapphire screen as the top component that they hoped would come with the next device.

More importantly, 50 percent of all Android and iPhone users said they would ditch their current device for a new iPhone if it included a sapphire screen, according to the survey.

On CNBC's "Fast Money," uSell.com Co-Founder and COO Nik Raman shed some light on why customers are so eager to see an iPhone with a sapphire screen.

"One thing that we see is that 40 percent of users actually have damaged phones, so I think a lot of the guys who are selling their phones have cracked screens," he said Monday. "And that's why this sapphire innovation is going to be big for consumers."

The survey also asked about the importance of improvements to current iPhone features.

A rumored larger screen has been noted as a key selling point and a way for Apple to keep up with Samsung's offerings.

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ISI Group analyst Brian Marshall recently said that a bigger screen could be the catalyst behind the "mother lode of all upgrade cycles."

But according to uSell.com's survey, 37 percent of customers listed improved battery life as the most important improvement compared to just 19 percent who said they cared most about a bigger screen.

Apple finished the day up by 1.2 percent. Meanwhile, sapphire crystal company GT Advanced Technologies, which is rumored to be a supplier of the next iPhone, climbed 5 percent on the day.

—By CNBC's Michael Newberg