It appears that your set was manufactured in the Shantou/Chaozhou coastal area of China. I could not find exactly the same mark as yours, but a type of porcelain that looks very similar to yours was manufactured in the same area. It actually looks as if the pieces came from the same factory, possibly from different batches. One mark says Chaozhou, the other (yours) seems to say Shantou, which is in the same vicinity. Judging from the manufacturing date given for the other set, your set is probably no more than 50 years old. I have no idea of the collector's value of your set.