Well, they are a very underrated gemstone. Can be found in the areas only in the southwestern part of America, and some parts of mexico. Havent been found anywhere else in the world.
Have a similar color play to fine black opal, only much harder and they don't lose their color. Opals tens to dry out because water inside the stone gives opal its color. This isn't the case for Fire Agate, Iron Oxides coat the layers of agate and light passing through them Interfers with it giving it a rather beautiful shiller effect
Much like if you have oil in your garage and you get the hose and wet the oil spil, you will see rainbow colors in the sun. This is what is going on inside the Fire agate