Ian writes, “I was at the mine of origin for the unheated stones yesterday; and I have attached two photographs. It is midnight here in Ratnapura. I will be up for another 4 or 5 hours tending to clients back home. Then, I will be back out in the field, unreachable until around this time tomorrow.”
“blown” is a traditional method of heating used in Sri Lanka. It is accomplished by packing the rough stone in coconut shell, lyme and embers; and then heating it by blowing through a tube. This is typically at lower temperatures. And the results are dependent upon the skills and experience of the Lapidary.
This methodology (versus kiln heating performed in Thailand) achieves results more typical of mother nature.