We exclusively reported that the Samsung Galaxy S III will feature a ceramic case, but looking at Samsung’s Unpacked event invitation that went out Monday morning, it appears that there could be another material in play as well. It looks like it’s a brushed blue metal, possibly aluminum or stainless steel, but it could also be a brushed blue plastic — Samsung smartphones have made use of plastic cases with a brushed finish multiple times in the past. Lastly, we have heard from a trusted source that the Galaxy S III will feature a physical home button in the middle of the device under the display, and it won’t use the on-screen navigation buttons Google introduced in Android 4.0 Ice Cream Sandwich.