Unless you know a lot about diamonds, it is easy to be deceived by the sparkle of a good imitation. Your best assurance that you will get the quality you pay for, is to buy from a reputable jeweller or gemmologist.
The grade of a diamond and its value is determined by four characteristics.
Diamonds are cut in different shapes. Some common terms used to describe the shape or cut of diamonds include pear, oval, brilliant or round, marquise, baguette and emerald. Proportions, table diameter, facet angles and symmetry are some of the major factors in cutting which determine the stone’s ability to handle light.
Diamonds range in colour, from colourless to shades such as canary yellow, champagne, cognac brown, sky blue and green. So-called “colourless” stones are rated in terms of their paleness and transparency on an alphabetic scale ranging from D to Z. Stones rated “D” are completely colourless. Stones rated “Z” are yellow in hue. This system of colour grading is based on the GIA (Gemological Institute of America) standards.
Some diamonds are clearer than others. They contain fewer tiny imperfections or “inclusions”, invisible to the naked eye, than cloudier stones. Clarity is expressed by the following abbreviations: IF (internally flawless), VVS (very very small inclusion), VS (very small) SI (small inclusions), I1, I2, I3. Flawless is the highest rating in terms of clarity of the stones. This range of clarity is based on GIA standards.
One thing that obviously distinguishes one diamond from another is weight. This expressed in “carats” (or the abbreviation “ct”). One diamond carat weighs 0.2 grams or 200 mg. Therefore, a ¼ carat diamond (0.25ct) would weigh 0.05 grams or 50mg.