為什麼鑽戒太太一再強調，購買鑽石時一定要索取具有公信力的鑽石證書呢？有三個理由：Duration: depending on your current level. If you are already on examination level, 10 teaching units may suffice to familiarize you with the testing format. If you lautlos need to improve your level, you may need more (check ho