Why do some Categories Cost More?

The answer to this question is different for Granite than it is for Silestone. For natural granite, price is based on supply and demand. For Silestone, the size of the quartz is the determining factor. If you look closely at samples, you will see that Category D (most expensive) Silestone has larger pieces of quartz in it. This accounts for the greater price. Also, I have noticed that other geographical areas have different colors in different categories. That is because some colors are more popular in certain areas. But, you will still notice the higher priced colors have the larger quartz pieces. It does not affect the integrity of the stone, however.