A few thoughts came to mind.
What if the previously discussed kirtles are meant to be worn under a gown, so that the cloth part doesn’t show and only the trimming is visible? That means of course that the trimming is so wide that it covers the hem and the front of the skirt. But then again some of the skirts itself are decorated with velvet, so maybe they were supposed to show.
Another thought occurred while browsing through portraits. I found similarities to the two-colored kirtles only in German and Flemish pictures*) and remembered that in the Dowry there are two kirtles described as German. The color of the kirtles is not mentioned, and both are listed under brocades. The other is of “smooth flower brocade with brown silk” and the other is of “smooth brocade and yellow silk”. The silk parts fit to the kirtles in the Inventory, but wouldn’t they have mentioned if the cloth was brocade? There also are two black cloths for the neck listed in the Dowry, and we know that the black partlet is an essential part of the German dress. So these matters may point to the German area.
Funeral gown of Anna Jagiellon, 1547
Furthermore, the funeral dress of Catherine’s cousin Anna, who was the queen of Hungary and Bohemia, resembles Saxon gowns and the more widely known gown of her sister-in-law Mary of Habsburg, who was the queen before her. Mary’s dress is dated to 1520’s, and Anna wore hers to the grave in 1547. A 1520’s dress is certainly too old to use as a reference for the beginning of 1560’s, but is a dress that’s only 15 years old too outdated? Remember that Catherine’s famous Spanish dress was at least nearly ten years old when she packed it with her to Finland.
Dress of Mary of Habsburg, 1520’s
Looking at Mary’s dress it’s easy to get the idea of a bodice that differs in color from the skirt, and the same contrast color is used also for the sleeves. However in the description it says that the sleeves are decorated, not hemmed, with the black velvet, so they might look more like the ones on Anna’s dress.
There is even earlier proof that real two-colored kirtles existed, even though the sleeves here are made of the same fabric as the bodice. The picture depicts Catherine’s aunt duchess Jadwiga, who died 1502.
There’s also Catherine’s sister-in-law Barbara Radziwill’s regional dress that’s depicted in c. 1550. It resembles considerably Jadwiga’s dress, even though they have 50 years in between. So could it be possible, that Catherine’s two-colored kirtles look something like Barbara’s and Anna’s dresses?
And I thought this was going to be easy. I’m probably making this more difficult than it actually is.
*) I am aware that there are two-colored kirtles elsewhere too, but the majority has the skirt and the bodice made of same fabric while the color of the sleeves is different. I am looking particularly for kirtles with skirts and sleeves made of same fabric and bodices of other, and these -or at least kirtles with some resemblance to these- were found in the Germanic regions.