You can get a good deal of information about Zia pottery online. The buttons were made in the early to mid-20th c. (for the automobilers) and I think the artisans are still throwing pots today. This is a large thick fired red pottery, 1 & 5/8", decorated with 3 or possibly 4 colors (if the rectangle is not painted). It is in excellent condition. These buttons have abstract designs and natural subject as well like birds.