Oh my, these hand tatted inset corner trim pieces are just gorgeous! The vintage embellishments date from the early 1900's - 1930's, are in unused condition, in an ivory color.  The thread is cotton, possibly a pearl cotton, as the trims have a slight sheen. 

Length along the bottom edge to the corner on each of the sides is 13-1/2".  Measurement along the top edge to the corner is 9-1/4" on each of the sides.  Width of the trim is 3-7/8" wide. 

Magnificient for many project applications.  One I could see, would be an addition to a vee neck line.  However, let your imagination be your inspiration.