Diamond value is based on four char

Diamond value is based on four characteristics: carat, color, clarity, and cut. A diamond’s size is measured by carat weight. There are 100 points in a carat and 142 carats in an ounce. Each point above 1 carat is more valuable than each point below 1 carat. Thus, a stone that weighs more than 1 carat is more valuable per point than a stone that is smaller than 1 carat.
The scale used for rating a diamond’s color begins with “D,” which means the stone is absolutely colorless and therefore most valuable. “E” and “F’ are almost colorless. All three are good for investments. A stone rated between “G” and “J” is good for jewelry. After that the stones take on a slightly yellowish color, which gets deeper as the grade declines.
The clarity of a stone is determined by its lack of carbon spots, inner flaws, and surface blemishes. While most of these are invisible to the unaided eye, they do affect the diamond’s brilliance. For jewelry, a diamond rated VVS1 (very very slight imperfections) is as close to flawless as one will find. After that the scale goes to VVS2, VS1, VS2, SI1, SI2, I1, I2, and so on.
The final characteristic is cut. When shaped (round, oval, emerald, marquise, pear, or heart), the diamond should be faceted so that light is directed into the depths of the prism and then reflected outward again. A well-cut diamond will separate the light into different colors when the light is reflected. Only stones of similar shape should have their reflective qualities compared, as some shapes are more reflective than others. For example, the round shape is the most reflective.