All genuine Valampuri Shankhas are Holy items associated with Goddess Lakshmi. However based on size, looks and rare features they are classified as follows:
Jewel quality : This type Valampuri has a very good luster, very neatly shaped and very beautiful to look at.
Rare quality : Normally Valampuris have 3 to 5 circular rings (called sutures) on the head portion and 3 to 4 horizontal ridges (called pilae) on the opening cavity. Valampuries with more than 5 sutures or 5 or more pilae are classified as rare quality Shankhas.
Based on sizes and weight the Valampuri Shankhas can be classified into five categories.
1) Mini Size : 2 to 3 inches in length, about 1 to 1-1/2 inch width and weight 25 to 50 grams. The shell is very thin so most people don't take the risk of cleaning or polishing this mini ones. So it is mostly sold with skin. the whrols (circular rings) on the conch head are also not well developed in this size.
2) Small Size : 3 to 4 inches long, 2 to 2-1/2 inches wide and 100 to 150 grams in weight.
3) Medium Size : 5 to 6 inches long, 2 to 2-1/2 inches wide and weight about 250 to 400 grams. This is the most commonly available size.
4) Large Size : 6 to 7 inches long, 2-1/2 to 3 inches wide and weight 500 to 800 grams.
5) Giant Size : 8 to 10 inches long, 3-1/2 to 4 inches wide and weight range 1000 to 1500 grams.