Rings with prong settings should be checked yearly to be certain that the stone hasn't become loose. Channel Settings Channel settings are one of the most misused settings in the industry. When there is a real channel, the stones will not come out under normal wear. Metal Quality Finely made rings have a quality mark imprinted on the inside. Kt gold is considered too soft.
Platinum tends to show very little wear as it is more durable than gold.
Electrolyzed or plated metal will often wear out on rings. High quality rings can be re-polished by a jeweler if they get scratched. There is a huge range of gemstone quality. Generally, looking for stones without imperfections and with good color is a great place to start. Additionally, check out how well the stone is cut.