1. Diamond Buying Guide

"Diamond is the women's best friend'. To buy diamonds safely, expert suggest how to evaluate the quality of each diamond by using use four standard measurements to compare and evaluate each diamonds : Cut, carat, clarity, and color. Once you get to know the four Cs, you can make informed tradeoffs based on your style preference and budget.


The first 'C ' - Cut



Diamond shapes range from traditional round cuts to hearts, pears, and more. A well-cut diamond reflects light to maximize the stone's brilliance. Cut has three components:



Diamond cut grade: A standard grading report describes cut by the shape or outline of the diamond and the pattern of the facet arrangement (also known as cutting style).
Diamond cut depth: Diamonds cut too shallow or too deep lose light through the bottom or sides, causing the stones to sparkle less.
Diamond polish: A poor polish, or rough facets, can diminish a diamond's brilliance, as well as its value.


The second 'C '- Carat



Diamond size is measured by weight in carats or points. 1 Carat = 100 Points = 200 milligrams. Diamond prices rise considerably as carat weights increase.


The third 'C ' - Clarity



Most diamonds contain inclusions (tiny mineral traces or flaws) often invisible to the naked eye. A diamond's clarity is determined by the amount and severity of these inclusions. Flawless diamonds are very rare and more expensive. Diamond sellers often describe the clarity of larger, solitaire diamonds by referring to the industry letter grading scale. For example, the International Gemological Institute (IGI) uses the following grading scale for clarity:


The last 'C ' - Color



Most diamonds appear white to the naked eye, but they all include trace amounts of yellow color, with the most valuable diamonds falling in the colorless range. However, a deeply colored diamond such as a brilliant canary yellow diamond can cost more than its colorless counterpart.
Fancy diamonds, also called Z+ diamonds, come in a variety of colors including deep yellow, pink, orange, blue, red, and black.

Beside from these '4C' , many sellers include diamond appraisal (estimated retail value) and certification information in sellings. Certificates, official documents issued by third-party gemological labs, include specifics about an individual gem (at least the four Cs) independent of market value. It can include information about diamond quality, validation that a diamond is organic, and the serial number on the girdle of laser-inscribed diamonds.



To buy a quality diamond:
You have to look for reputable gemological labs: Make sure a reputable gemologist or gemological lab issued the grading certificate.
If you buy diamond online such as via ebay or amazon, you should evaluate the grading certificate's photo: Look for listings with a picture of the grading certificate and its serial number. Some labs offer online services where you can type in the serial number and verify that the lab graded the diamond and that the specifications are the same.
Finally, you should discover the origin of a diamond: Ask sellers for more information about their process for confirming the origin of their diamonds so you don't end up buying a conflict diamond.

Main reference ; from ebay review (http://pages.ebay.com/buy/guides/diamonds-buying-guide/#1 and http://review4best.blogspot.com/2008/02/2-diamonds-buying-guide.html)