The color of a tooth is determined solely by the color of sediment in which it is buried while fossilizing. The tooth absorbs minerals from the surrounding sediment. As the minerals replace the natural structure of the tooth, the tooth becomes the same general color as the sediment. Therefore, color is not an effective indicator of the age of a tooth. The most common color for shark teeth is a black root with a grayish crown.
Different colors are more uncommon and significantly increase the value of a tooth.
Shark Teeth in my Catalog and History of the megalodon. During this time period oceans sporadically covered many parts of what is now the Southeastern United States. Most of the teeth from these locations are between 3 and 10 million years old. I specialize in teeth from the Carcharocles megalodon shark which thrived during the above time period. This shark was the largest shark to ever swim the ocean.