Can you tell if there is dye in sapphires by sight alone? I recently had a seamen schepps sapphire and other gemstone bracelet appraised. The appraiser expressed that he felt some of the sapphire cabochons were replaced with dyed sapphires. This was done by shining a bright "torch" light into the sapphires and pointing to high color concentrations near the surface of the stone. I though a lab would be needed to determine this as it couldn't be done by sight alone.