Carat refers to the unit of measurement used to weigh gemstones. The term comes from the seed of carob tree which was used to weigh precious stones in the ancient times. One carat is equivalent to 1/5 of a gram and it is further divided into 100 points. A diamond with 50 points is ½ carat or 0.50 ct. The price of the diamond rises exponentially with size. Large gems are very rare compared with smaller ones and definitely, they cost huge amount of money.
Clarity is often assumed as the most important factor. This is because it gives the gem a profound visual effect. Clarity depends on the internal and external features referred to as the inclusions and blemishes respectively. The irregularities come from the volcanic rock. Originally, diamonds are made from pure carbon and while the stone forms, minerals nearby become trapped causing the imperfections. Experts assess the stone using ten times magnification under a standard light. The number, size and visibility of the inclusions determine the clarity of the stone. Internally flawless diamonds are definitely more expensive since they look more brilliant and beautiful. Grading ranges from flawless to heavily blemished.
Cut is not just about the shape of a gem. It is how the stone returns the light back to the viewer’s eyes. It is the most challenging of the four C’s. Cut affects the brilliance and sparkle of diamonds. A high grade gem allows light to pass through it, reflects and refracts it internally and produces a dazzling effect and play of colors called “fire”. In simpler terms, a well cut stone should catch your eyes. Incorrect cutting of diamond creates a dull looking and lifeless stone and thus, this will cost less. Rating based on cutting is expressed as excellent, very good, good, fair and poor.
The ideal diamond quality is colorless but this is extremely rare. Color scales range from no color at all to deeply colored or rating of D to Z. Grading can be done using a colorimeter machine or manually by comparing the gem with a “master stone”. Less expensive types are off-white, mucky yellowish or brownish color. They absorb light instead of refracting it and thus, inhibiting its brilliance. Normally, colored diamonds have lower rating and are less expensive than colorless jewels.
Some jewelers consider another C in grading diamonds. They include Certificate in the evaluation. This is also called as the grading report. It is provided by highly qualified professionals in the industry using advanced gemological instruments. The certificate contains the individual characteristics of the stone.