Rumors about the successor to Apple's iPad mini have been circulating on the Web, but now a rumor has come up with proof.

Pictures of the rear panel of an Apple device have surfaced on the Internet, and the panel is believed to be on the upcoming iPad mini 2.

The shell or panel shown in the pictures looks very similar to that of the current iPad mini but the thickness of the panel is in question. The panel looks a little thicker than the first-generation iPad mini.

Many people are linking the thickness of the panel with Retina Display, but some are of the opinion that the thickness is increased to give the tablet an improved and advanced battery.

The pictures were posted by a Chinese Web site weiPhone, but the source of the images was not disclosed in the thread.

According to earlier rumors, Apple's iPad mini 2 is said to be coming out with a 7.9-inch 2048 x 1536 pixel high-resolution Retina Display. The pixel density of the second-generation iPad mini will be four times greater than its predecessor.

Meanwhile, a recent report has suggested that introducing the Retina Display in the iPad mini 2 will increase the total production cost by around 30 percent: equal to about $12.

According to a DigiTimes report, the iPad mini 2 with the Retina Display will have a bill of material (BOM) of about $200.

Quoting the figures predicted by iSuppli, the report suggests the price of the 7.9-inch panel is around $32/unit and the total material cost of the entry-level iPad mini is around $188/unit.

"If iPad mini adopts the Retina display, the dots per inch (DPI) will be higher and the brightness of the backlight modules will have to improve. This also means the number of LEDs used will increase, and therefore market observers believe the total cost for iPad mini will increase by more than 30% if it is equipped with the 7.9-inch Retina panel," the report says.