The value of a diamond depends not just on size but cut and clarity too. A 1 carat diamond can range anywhere from about $1000 to several thousand dollars. I think an average price for a very good diamond is about $8000.
1 Additional Answer
How much a 1 carat diamond is worth depends on several things. The size, grade, color, cut, and whether it is in a setting or not will all affect the cost. A 1 carat diamond of fine quality can range from $4,800 to over $7,000.