Ruby & Sapphire heat treatment.Ruby & Sapphire heat treatment and other surface repair such as with resins and glass filling and heating them up in a special oven this is the domain of the "Ruby Burner" in Chanthaburi and almost all ruby stones from the Mong Hsu Mines are going through this procedure because the quality is not good enough.
By using temperature the gem can get different colors this is the same with sapphires and other corundum stones. Sometimes the producer enhances the stones by a heating process which makes the stone more saturated and brilliant too. If it is made is must be declared to the customer because if this precious item is sold again and carefully inspected the enhancement show up and the price drops dramatically.
In general when buying any ruby or sapphire rings for more than about $ 1000,- have the item checked in an independent lab because lots of dirty tricks are going on in this business and don’t believe any certificate or talking of the sales person that is only sound and smoke. Actually, it is a common problem with all these precious stones.
After the stones left the country to let's say for Thailand India Singapore Europe or Israel the prices make a jump upwards and people in those countries make the real profit by cutting polishing and manipulate them.