There is a grayish green color that will blend in with almost any color darker than tan. It might be called camouflage green but that doesn't sound right. A lady on one of my yahoo quilt groups always uses it to applique and her stitches are invisible. I don't like the feel of any of the invisible threads--nylon or poly. They both feel like fishing line to me and I want my quilts to be soft. Personally, I would just use the white or off-white all over. That seems to be the most time honored quilting thread color of all and never looks wrong.