The key difference between Travertine and other natural stones lies in the formation of the rock, the hardness of the stone and the appearance. Travertine is formed in hot springs and/or limestone caves. Key characteristics of Travertine stone are the holes within the stone which are caused by carbon dioxide evasion. Travertine Tiles are natural stone tiles where the holes have usually been filled. Some of the most popular colors are Ivory, Beige, Walnut colors (light, medium, dark), Noce (Dark brown), Silver and Gold. Combinations of these colors are also possible.