The most skilful connoisseurs distinguish forty-three varieties of Bengal indigo. The most important are the following:—
1. Superfine blue, light or floating.—Color bright blue; light, friable, and spongy; adherent to the tongue, soft to the touch, showing coppery reflections when rubbed by the nail; paste uniform and pure.
2. Fine blue.—Like the preceding, but the color a little less vivid.
3. Violet blue.—A little less light and friable. Has a violet blue.
4. Superfine violet.
5. Superfine purple.
6. Fine violet.
7. Good violet.
8. Red violet.
9. Ordinary violet.