The final result is that a 1 carat round D flawless diamond would cost between $12,500 and $15,000. And a 1 carat round diamond with A G color, SI1 clarity, and exceptional cut, like the one I recommend, would cost $6,000. A study of large diamonds sold at auction reveals that flawless diamonds are extremely rare: out of more than 100 large diamonds sold at auction during the last decade, only three were considered "D" or "E" quality, which is why my estimate seems low. However many other factors can affect price, such as color, shape, weight, and setting. A colored diamond may look attractive, but it will also cost more to repair the damage caused by exposure to light. As for shape, well, round diamonds are easier to sell if you're looking to make money quickly, while fancy shapes tend to be more valuable. Finally, price depends on demand and supply. Flawless diamonds are so rare that there is no competition between sellers, which means they can ask any price they want. On the other hand, since there are many less-than-perfect diamonds available, buyers have some choice about where to spend their money. If you ask me, it's not hard to guess what role market forces play in determining diamond prices. In conclusion, a 1 carat flawless diamond costs between $12,500 and $15,000.