How was the red colour of carnelian beads achieved?

By firing the yellowish raw material and beads at various stages

In Chanhudaro different techniques were employed to make beads based on the material used. Steatite, a soft stone, was easily worked, and some beads were moulded from a steatite powder paste, allowing for various shapes. In contrast, harder stones were used for geometrical forms. The methods used to create microbeads from steatite remain a puzzle for archaeologists studying ancient technology.

Archaeologists' experiments have revealed that the red colour of carnelian beads was achieved by firing the yellowish raw material at various stages of production. Nodules were initially chipped into rough shapes and then finely flaked to obtain the final form. Grinding, polishing, and drilling were the final steps in the bead-making process. Specialized drills have been discovered in Chanhudaro, Lothal, and Dholavira.