How to evaluate a Gemstone based on Carat Weight?

Every gemstone is sold on the basis of carat. The carat is a unit of weight like gram, kilogram, ton etc. However, due to the small size and different factors involved in the evaluation of the gemstones, they are sold on per-carat basis. It is wrongfully referred to as a unit of size. Two gemstones with same size can have different carat numbers, and vice versa. It should not be confused with the word Karat used to measure the fineness of gold.

Let us define how gemstones are measured and sold for their value on per-carat basis.

What is carat?

Carat (ct.) is derived from the Latin word carato or carob. Gemstones in ancient times were cut in a way that they resembled the seeds of carob. Even during the classical times, there was a clear distinction between the definition of carat and karat. Carat values were different for different countries as there was no international standard of measurements.

The first instance of using carat as a unit of measurement is recorded in 1570s. The diamonds, for obvious reason was the first gemstone to be calibrated on carat basis.

In 1880, the value of carat was approximately 3.17 grains. In European countries, two carat values were established to measure faceted hearts and faceted squares. They were:

-  Pound carat
-  Ounce carat

In UK, the popular carat value was called the Refiner’s carat. In terms of milligrams, the value of carat shuffled between 180 mg and 220 mg across the world.

Why was carat standardized?

There are two reasons that led to standardization of the carat value.

1.   The growth of commercial gemstone industry:

Gemstones till World War II were largely mined from the European colonies in India, Malaysia, Thailand, Burma, China, Africa and South America. The traders had difficulty in buying different sized gemstones from traditional sellers. In order to establish uniformity of business, the carat value was officially standardized.

2.    Creating new cut and facets:

As the new cuts and fancy faceting techniques arrived in the industry, it became necessary to establish a standard value for carat. It ensured that the wastage of gemstone was minimized to a bare minimum. In case, the gem cutter erred in cutting the gemstone, he/she could be fined accordingly on per-carat wastage.

The carat standardization has reduced conflicts and confusions between traders of the gemstones across the world.
What are the different forms of jewelry that use carat as unit of measurement?

Gemstones are used in various jewelry items. The use of carat is common in trading of diamonds, emeralds, garnet, rubies, sapphires, topaz and other transparent gemstones. The various forms of jewelry are:

-  Anklets
-  Earrings
-  Bracelets
-  Belly chain
-  Navel ring
-  Brooch
-  Collar pink
-  Cufflinks
-  Lapel pin
-  Pendant
-  Tie clip
-  Toe ring
-  Watches
-  Belt buckle
-  Pens and glasses

No matter where the gemstone is used, the carat value will remain same.

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