Your answer depends entirely on the diamond, its cut, carat weight, clarity and colour.
The streak of diamond is white; quantity -- how much -- isn't a factor.
No, diamond is MUCH harder.
I think you are asking if a natural clean diamond is worth as much as a natural diamond that is Not considered clean? The answer is no. A clean diamond means that it is clear from imperfections. Now this can mean clear to the naked eye, or clear under a microscope. Of course the diamond that is clear under the microscope is much worth more than a diamond that is only clear to the naked eye.
First, understand that if your 'one carat' diamond has '80 points', it may not weigh one carat. Then, take your diamond to a certified gemologist who can tell you 'how much' can be attributed to your diamond.
This depends entirely on the diamond in question.
Two
5$
Not much of a price decrease, a $2000 dollar diamond can still have a scratch or a crack,
Any diamond is worth whatever someone will pay you for it.
Your answer depends on the quality of the diamond you're buying/ selling.
Take your diamond to a certified gemologist who can help you value the pieces.
Any diamond is worth whatever someone will pay you for it.