This color is not part of a commercial set, however it is mentioned as part of Williamsburg’s six Chromatic Darks. From their publication, Just Paint they explain, “These colors are all blends, containing a natural iron oxide or Ivory Black and one or more strongly colored pigments to give them their chromatic punch. When painted from the tube, they visually resemble a colorful black, but when scumbled, tinted or mixed, these darks start to show their true color!” In regard to this color specifically they say, “Turkey Umber is a mixture of Raw Umber and Phthalo Green. It is one of those combinations that makes sense when you see it, but may not be something one would normally mix together. It is a Semi-Opaque, finely milled, fast-drying color that can be used in combination with an earthy red or Burnt Umber as a warm cool underpainting palette, or used as a dark, neutral green to hold down a landscape painting. Turkey Umber is a great alternative to Raw or Burnt Umber to reduce intensity with a little bit of a twist.” -Just Paint, 2020. Also, Williamsburg recently published new lightfastness results for various pigments. While this blend is not specifically mentioned, the tests on its individual ingredient pigments are interesting. For more see https://justpaint.org/astm-lightfastness-testing-for-oil-paints/