Answer:
Here are six. Pick any three you like. ;-)
This is not actually a real diamond. It is a good imitation.
This is not actually a real diamond; it is a good imitation.
This is not actually a real diamond, but it is a good imitation.
Although this is not actually a real diamond, it is a good imitation.
This is not actually a real diamond. It is, however, a good imitation.
This is not actually a real diamond; however, it is a good imitation.
Step-by-step explanation: