There are shankhas with different colors (varna) and the colors are related to castes.
Brahmana: These are white in color, smooth in texture and light
Kshatriya: These are red colored, or brown-hued, heavy, rough and course
Vaishya: These are yellowish in hue, glossy, thick and light
Shudra: These are dull grey or dark brown in color, hard and heavy
This classification, however, is neither exhaustive nor accurate. There are six types of auspicious Shankhas known as Shad Shubha Shankhas. Of the above, the Vamavarti and Dakshinavarti are the well known ones. These two types of shankhas are used in the left and right hand respectively. Those with left ward convolution are called Vamavarti or Turbinella pyrum dextral. It is the brother of Laxshmi and a friend of Vishnu. Shankhas with right-ward convolution are called Dakshinavarti or Turbinella pyrum Sinistral. Vishnu held the right handed shankha in his right hand at the churning of the ocean of existence. Lakshmi was born from the churning ocean and then Vishnu married her. The right handed conch bestows prosperity when worshipped. It is placed on a red cloth and worshipped with white sandalwood mixed with camphor and saffron, flowers, rice, incense, and light. The conch can be worshipped as Vishnu and Lakshmi and helps to solve financial problems. If Skanda purana lauds the Vamavarti shankha, as all accomplishing, there are many texts like Samkha kalpa, which claim that the right oriented Dakshinavarti Shankha or Valampuri Shankha and Lakshmi Shankha, are the most auspicious and beneficent, and also that its worship will bring forth all benefits.