This stomacher, dated to the 1770s (though it may be earlier—see discussion below), is in the collection of the Nordic Museum. I found it through the database of Swedish and Norwegian museum artefacts,
DigitaltMuseum. The item
text says (in translation):
a) Stomacher, triangular with the lower point rounded, out of two layers of white linen with 6 silk rep ribbons sewn on close together, striped in white, red, and pink, each with a bow in the center.
b) and c) Separate bows.
So, this échelle stomacher comes with two matching bows for attaching to the sleeves, making it a complete set as seen in many period portraits.
