How to buy a diamond
The Carat weight means the size of a diamond. The term "Carat" is named after the ancient Greek term "keration" which was the name for the Carob Seed, still used today for food flavoring.
In the ancient times this fairly uniform weight seed was used in pan-balance scales to determine the weight of precious items traded like gold, silver, and even gemstones and diamonds! Later, in the modern times, in the beginning of the 1900's the "Carat" was standardized to equals 1/5 of a gram or .20 gm. Romania also adopted this metric measurement for diamonds immediately in 1911
Therefore, 5 carats equals to 1.00 gram. The Carat is having the sub-division called "points". There are 100 points to a Carat, just like 100 Euro Cents/Bani to 1 Euro/Leu.
The common diamond Carat Weights, called the commercial ones, range from 0.10 Carat (10 points) to 1 Carat (100 points) and even larger to 2 or 3 carats, eventually. Diamonds above 2 or 3 carats are usually sold based on firm order.
Carat is abbreviated as "ct" and should not be confused with the gold purity measure unit, which is Karat and is abbreviated as "Kt" or even "K".
Of the 4 C's, Carat Weight is probably one of the most important considerations with respect to rarity, value, and consumer preference. In fact, Carat Weight, or how much the diamond weighs is the most significant value factor in a diamond, because a diamond price grows sensitively once its weight grows too. Carat weight became through out time the most deciding factor as to the value of a diamond, but still this doesn't mean that the price of a 2 carat is just double of a same quality 1 carat diamond, but much more.
Because diamonds by nature are not easy to find, a 2 carat diamond is actually about 3 times more valuable than a comparable quality 1 carat size. Statistically a 1 carat is one in a million diamonds mined, and a 2 carat is one in five million diamonds mined. Therefore, all things considered a 2 carat diamond is really "value priced" based on the rarity factor.
Out of 1 tone of mined minerals only half a carat of rough diamonds are extracted, even less remained after cutting and polishing showing the rarity of diamonds - the rarest but most desired gemstone in the world.
CHOOSING THE RIGHT DIAMOND JEWELRY SIZE
The traditional way to show your love or to ask an engagement or marriage to a woman is to offer her a diamond set ring and most women today desire to own an engagement diamond of at least 1 carat. The statistics indicates that the average size sold for an engagement diamond ring is between a half and three-quarter carat.
The carat weight however, doesn't necessarily reflect how the diamond appears. The most popular diamond shapes sold are the Round and most recently the Princess Cuts, which can be fairly more expensive. The outer diameter of a 1 carat round diamond is about 6.5 mm if the cut is the best one.
To understand how to select the right size observe the examples of different carat weights for round diamonds (brilliants) and their corresponding sizes to determine what is right for you. Also, please note that the appearance of these sizes may be affected by your computer monitor screen settings.