There is provided a method for assessing the integrity of grip of a stone in a jewellery setting having plural gripping claws to grip said stone, the method comprising heating the stone; measuring conductive transfer of heat from the stone to each of said plural gripping claws; and comparing said conductive heat transfer to said each gripping claw, wherein a marked difference in conductive heat transfer to any of the gripping claws indicates a lack of integrity of grip. Suitable apparatus is also provided.