Most people are familiar with the principle, “the higher the carat weight the greater the value.” However, in actual practice, this principle is more complicated than it appears. This can be illustrated by having you determine which emerald ring described below is more valuable. Assume that the quality and shape of all the emeralds are the same and that the two ring mountings have equivalent values.
Strangely enough, a single one-carat emerald would normally cost more than 1.50 carats of small emeralds of like quality unless the emeralds were of a very low-grade. This is because the supply of large emeralds is more limited. So when you compare jewellery prices, you should pay attention to individual stone weights and notice the difference between the labels 1 ct TW (one carat total weight) and 1 ct (the weight of one stone).
When comparing the cost of emeralds, rubies and sapphires, you should also start noting the per-carat cost instead of concentrating on the total cost of the stone. This makes it easier to compare prices more accurately, which is why dealers buy and sell gems using per-carat prices. The following equations will help you calculate the per-carat cost and total cost of emeralds.
- stone cost
- per-carat cost
- carat weight
- carat weight x per-carat cost = total cost of a stone
The per-carat prices of emeralds are listed in terms of either their weight or millimetre size (unlike those of diamonds, which are usually only listed according to carat weight). Stones over 1/ 2 to 3/4 of a carat are generally priced according to weight, whereas those under 1/2 carat tend to be listed in terms of millimetre size.
Price/weight categories for coloured stones vary from one dealer to another and the categories are often broader than for diamonds. A one-carat price level for an emerald may extend down to 0.85 carats. Depending on the quality, sometimes, a larger weight brings a lower per-carat price. However. you should expect a fine 4-ct emerald to cost considerably more per carat than a one carat stone of the same quality.
Since price/weight categories vary from one dealer to another. there’s no point in listing any. Just be aware that shape and carat weight can affect the per carat value of emeralds and follow these two guidelines:
- When judging prices, compare stones of the same size. shape. quality and colour
- Compare per-carat prices instead of the total cost