The rough stone requiring heat treatment. (right side one)
By subjecting this rough stone to a high temperature heat treatment
It improves the look to a level that is considered fit for sale.
On the other hand, the ruby on the left in the photo below is beautiful
without any processing.
At this raw stage, the ruby's value is already determined.
Even if the heated ruby is beautiful after processing, the bottom line is,
its value was already determined at the rough stone stage.
Crucial point when deciding on a gemstone.
This is why Mori's continues research to keep up with the processing techniques.