The most popular color is the brown affiliated color circle contact lens among all kinds of different contacts. The variation of brown contacts is very broad.
Among them, the hazel contacts are the most popular one. There are not much brown color contacts if we take out little bright hazel contacts, and dark hazel contacts.
Brown contacts are divided into two groups: the hazel category and the non-hazel category.
However, depending on the person, the color looks different even with the same hazel contacts(same product) worn. This is because the eye color is different from person to person.
more info
https://medium.com/@hazel_contacts/natural-looking-hazel-contacts-vivid-looking-hazel-contacts-b6b53ceca232#.d2is522rg
https://topstarcontacts.wordpress.com/
http://criclelensestool.bravesites.com/