You need to be level 23 or more. When you have this level, you can tell the smith to make amber armor, and it will be Perfect. On lower levels, you will only get weaker versions of the Amber armor. (Level 1-3: Impure, 4-7: Lesser, 8-11 is only called Amber, 12-16: Fine, 17-22: Grand and 23+: Perfect)