Sapphires are now being induced with colour and clarity enhancement agents so as to achieve a better market value for the unsaleable stones. It has been recorded that colourless low grade Sapphires are being infused with cobalt, a colouring agents giving stones its desirable blue colour. The cobalt is also used with lead filled Sapphires, which fills fractures and also colours the stones.
In order to tell the difference between these stones and their counterparts the stones will appear red under the Chealsea filter because of the presence of colbalt.
Another definitive test could be through magnification as these stones will appear to have higher concentrations of colour in their fractures and show flashes of yellow, pink blue and violet colour on rocking and tilting.
Customers in this gemstone pipeline should be cautious and aware of these stones ending up on their table.