How to Select Diamond Carat Weight

By Robert Underhill


Carat weight is the psychological force behind diamond values. The average consumer is so overcome by the words Carat, Carat and a Half and 2 Carats that they sometimes become more important than quality. Most young men set out on a quest, believing they have to acquire an engagement ring of a carat or more. Statistically, most of those young men end up with 3/4 carats or less. Many of those who do procure a "1 Carat" diamond do so by forfeiting quality by settling for below average brilliance, yellow brown, or heavily flawed stones.

So what is a Carat? Carat is not a size or measurement. It is a unit of weight. In ancient times gemstones were weighed on a balance scale offset by carob seeds the word transformed to carat over time.

In nature, larger diamond crystals are formed less frequently than smaller diamond crystals; consequently, larger stones are more rare. This is unfortunate because ego and desire have created enormous demand for size. It's a simple case of supply and demand. Nature has not created as many large gem-worthy diamond crystals as there are women wanting to wear them or men wanting to give them. The net effect is that larger diamonds are exponentially more valuable than smaller diamonds of equal quality.

World diamond trading is done in U.S. dollars and prices are paid per carat. The price per carat increases according to stone sizes due to rarity and demand. Significant increases per carat occur when a stone exceeds bench mark sizes. The price per carat increases at 1/2ct, 3/4ct, 1ct, 1.5ct, 2ct, etc. The price paid per carat is higher at each increment if all other characteristics are equal. For this reason, a 1 carat diamond is exponentially more valuable than two half-carat diamonds.

These universal price brackets create shortages in certain diamond sizes. You will seldom find stones weighing .95ct or 1.45ct. Cutters who buy rough diamonds that would yield a .95ct ideal cut stone will profit more by cutting the crystal at less brilliant angles to make it 1 carat. Likewise, stones weighing 1.40ct will be cut to 1.50ct and stones at 1.90ct will be cut to 2.00ct size etc. By cutting the stones a bit chubby, they can increase the weight of the diamond that the rough will yield and cheat it into the next size bracket.

These stones do not have the same value as ideal cut diamonds, but as long as people covet stones that are a "Carat" there will be people willing to buy them.