Always assume that there are minor inclusions or damage under the prongs or bezel. Tilt the diamond so your view is in an angular direction under the prongs. This also displays a girdle reflection which may bring hidden inclusions into view. Remember not to confuse prong reflections. Looking under each prong from three possible angles gives you the best chance of a good educated guess. However, there is absolutely no way of guaranteeing a precise clarity grading in a mounting. Be conservative and you will seldom be disappointed.