Evaluate gemstones using the four "Cs": carat weight, color, clarity & cut. One carat equals one-fifth of a gram, the unit of measure by which gemstones are sold. Generally the heavier the gem, the higher the price. From the consumers' standpoint, much of that weight should be showing on the face of the stone, or the table. This is where the cut of the gem comes into play. If the gem is cut too deep, most of the carat weight is hidden from the eye & the colour may be too dark. A gem cut too shallow, on the other hand, will lack brilliance & have a flat, washed-out look. An ideally cut gem reflects light evenly from all parts of the table.