Tortoiseshell cat

I have just acquired a young (1 YR 4 MOS) female cat. She has the most amazing markings: a black stripe down her back and almost perfect mirror image markings on either side of it. When she stands up she appears to be wearing a leash because the lighter brown goes around her shoulders in two horizontal stripes. She has no red hair, just black and brown, with a white throat People tell me her markings are most unusual. She has very large ears and a small face for her size and talks a lot. She is a shelter cat, so I know nothing of her heritage, but suspect a good deal of Burmese ancestry.

Has anyone ever seen a cat with these markings?