The cause.The use of pigments that are stored for many years.To put the bridge in quantities too low (to keep the Golden shadow, obviously).Sintering temperature too high (so shiny clear golden)
The use of pigments that are stored for many years to put the binder in small amounts, too. (For want of a shiny golden obviously) sintering temperatures that are too high. (To be clear, golden shadow).
The cause.The use of pigment stored for several years.Adding binder in too little. (to the color gold shiny clear).Calcination temperature too high (for the color gold shiny clear).