Unlike the iPhone 5S, little is known about the iPhone 5C. The mysterious iPhone made its first appearance in July, when the first leaked image of its packaging appeared on the the Chinese WeiPhone forum. The rumor mill instantly assumed this was Apple's long rumored "budget iPhone," but nothing has been officially confirmed. The iPhone 5C has made numerous appearances since its initial leak, and it seems almost set in stone that Apple will unveil the new handset on Tuesday, September 10th. Here's everything we think we know about the low-cost iPhone.

Plastic Shell and Multiple Colors:

Various videos and images have revealed that the iPhone 5C will feature a plastic shell, and that it will be available in various colors. So far we have seen iPhone 5C parts in black, white, pink, yellow, blue and red.

Apple is expected to announce the iPhone 5S and iPhone 5C on Tuesday, September 10th at its headquarters in Cupertino, California. The iPhone 5S is the rumored successor to the iPhone 5, and the iPhone 5C is Apple's rumored plastic low-cost device. Here's what the rumor mill is saying about the iPhone 5S.

Design:

Apple fans are preparing themselves for another "boring" iPhone S-model launch. However, Apple is expected to spice things up with the announcement of a gold iPhone model, and the company has completely redesigned its OS. The radical new design of iOS 7 will help most people forget that the new iPhone looks exactly like the iPhone 5.

BlackBerry's Messenger app was submitted to Apple two weeks ago, according to a Tweet from a developer who worked on the app. It is unknown why the approval process is taking so long since the current approval time for the App Store is 4 to 5 days. Perhaps that is why the Senior Strategic Account Manager at BlackBerry, Alex Kinsella, felt the need to send a tweet.

The popular messaging platform was promised to land on both iOS and Android devices "before the end of this summer," by CEO Thorsten Heins in June. At least iOS users now know that it's not BlackBerry's fault for missing their own deadline.

More images of the iPhone 5S have leaked before Apple is expected to announce the rumored device on Tuesday. This time the alleged photos feature the iPhone 5S packaging. If you look closely at the box, you will notice the redesigned home button and new iOS icons. The iPhone 5S pictured on the package also features the same color-matched wallpapers seen in previous iPhone 5C leaks.

Both the iPhone 5S and iPhone 5C are expected to make their official world debut on September 10. Apple sent out press invites to the event on Tuesday. The invites include the tagline: "This should brighten everyone's day," and feature pictures of colored dots that resemble the redesigned iOS 7 icons. Some tech blogs have speculated that the random grey dots on the invites also hint at the iPhone's new home button with fingerprint sensor.

The Wall Street Journal reports rumors are once again surfacing that Apple is considering plans to introduce iPhones with screens between 4.8 and 6 inches, a significant increase from the current standard of 4 inches. These “phablets” would be a cross between a phone and the larger sized tablets already on the market.

While this is not something Apple is planning to announce this coming Tuesday, insiders are saying it is being considered as the company seeks new opportunities for expansion. The size increase would be the first since the iPhone was introduced in 2007.