To my eye an exquisite little thing--a fragment of a larger quilt, perhaps, or perhaps its maker had had enough! The method of making here was/is called English paper piecing--with each shape cut from a paper template, then wrapped with fabric, yielding a perfect, sharp-cornered octagon. (Much more common were hexagon quilts, typically arranged in honeycomb patterns; here, because of the octagons, and their linear arrangement, the maker interspersed tiny black diamond shaped pieces, made in the same manner, throughout.) This one was all done at a micro scale, making the construction all the more laborious! For me, the side showing that construction, with the paper and all the tiny hand stitches visible, is really the glorious one, and I'd frame this up with that side showing. 

6 7/8 x 5 1/4. Loss of a couple of octagons from the rectangle, as evident, and fraying to the fabric on a couple of bits. Structurally sound and stable and not especially fragile.