To protect the display of my Galaxy S4, I have this "mumbi Genuine Leather Case Samsung Galaxy S4 Leather Case Case (tab with retreat function) brown" risen. I must say, when I get this leather case, I was very pleasantly surprised by this. The quality of the leather case I would describe as a very good and also the S4 fits easily in this case, without too loose. The principle with the tab like it very much, as you can on the one hand secure the S4 before Entrutschen of Case's here, but also on the other, the S4 is nice to get out of this case.
I own a white S4 and after several weeks of use I can find no Verfärubung due to the brown bag on my device.
My conclusion: Super Case for the S4 with super quality, you get to an exceptional price. -> Buy recommendation!