According to NBTHK this tsuba was made by Kyoto craftsman. There where many schools and makers in Kyoto and when NBTHK can't decide which one of them is responsible for creating item in question, they give it a brooder term, Kyoto Kinko.
Tsuba is made of shibuichi which is an alloy of copper and silver. Shibuichi tsuba often have distinctive difference in color on the front and back. When melted more silver gathers on one side of the tsuba. That side will be used as a front, and in some places we will see more of the silver, grey, light green color. On the back of the tsuba there will be more copper so we will see much more of the red. This is more visible on seppa dai where some patina has been damaged.
Tsuba was polished and than different designs where gilded on the surface. It is very rare to see iroe (gilding) used to make a patterns on tsuba. With design like that usually we would see nunome-zogan or hira zogan.
This tsuba has a distinctive grayish color that I am afraid might be a little lost on the photos.