... .Good combination between alloy and porcelain, natural and special. PFM gold crown/ Au 52, AU 74, AU 89.There are three types ... of gold PFM crown, containing Au from 52, 74 to 89.1. All ... .3. Good combination between alloy and porcelain4. Good biological compatibility, gold colored base, which makes the porcelain more natural, special.5 ...