London Jewelers Newsletter

Volume 1, Issue 1 April 2010

A Guide to Buying Diamonds

Written by: Deborah Erickson (London Jewelers expert gemologist)

P urchasing a diamond is an exciting experience, but it can also be a mystifying one. Whether you are buying your first diamond, solitaire diamond, platinum or anniversary rings, or if you have bought diamond jewelry before, London Jewelers offers all the important facts you need to know about the 4 C’s of diamonds: Color, Clarity, Carat and Cut and using this knowledge to identify real diamonds. For 84 years, London Jewelers’ standards of quality, selection, value and service are legendary. Generations of families have shopped confidently at London Jewelers on Long Island. When you buy your diamond at London Jewelers, you can be rest assured that you have purchased exceptional quality at great value. Our own GIA-trained diamond buying team personally selects each diamond for the best combination of cut, color, clarity, carat, beauty and value. Below is information about buying a diamond and understanding the importance of the 4 C’s:


Cut is the single most important factor in determining the diamond’s beauty and value. Careful cutting is critical to a beautiful and valuable diamond. A diamond begins its existence as an irregularly shaped piece of crystal, sometimes call “rough”. When a diamond cutter buys a piece of rough, their job is to analyze the rough diamond to get an idea of what’s inside the stone. In looking to make the most of the rough stone, the cutter will locate the inclusion position and determine the most desirable shape that the piece of rough can be cut into while retaining most of its weight, possibly achieving a clarity grade one or two grades can be sold, for a higher price. When a diamond is properly cut by a skilled craftsman, light is reflected from facet to facet and then back through the top of the stone to your eye as brilliance. A stone cut carelessly, or too deep or too shallow, loses its fire and brilliance. The result is a stone with little sparkle of life… and much less value.


To accurately determine a diamond’s color grade using Gemological Institute of America (GIA) standards, the diamond is viewed table down, under controlled conditions and compared to a “Master Set” whose colors have been predetermined by the GIA. The color scale is in alphabetical order from D – Z, with D standing for “colorless” and Z for “fancy colors”. Although most gem-quality diamonds appear to be colorless to the untrained eye, there are subtle differences in shade, which in turn affect value. Diamonds with no traces of body color are extremely rare. Fancy colored diamonds occur in nature in shades ranging from pale yellows and pinks to vivid blues and reds; these vivid hues are rarest of all. Color does not have any direct impact on clarity. There are different grading systems for color and clarity.


Clarity is one of the “4 Cs” of diamond grading and another term for the quality of a diamond. Clarity is the relative measure of the number and size of the inclusions or blemishes that occur in practically all diamonds. Because diamonds form deep below the earth’s surface with extreme heat and pressure, combining with other minerals, there are many types of internal inclusions and external blemishes that make each and every diamond different. There are several different types of birth or growth marks in and on a stone, which internally are known as inclusions; marks on the surface are known as blemishes. The GIA clarity scale contains 11 grades, starting from a grade of flawless, with no inclusions or blemishes visible to a trained eye under 10X magnification, to a grade of Imperfect 3, the lowest clarity grade, where inclusions are large enough to be seen by the naked eye and may affect the durability of the stone. Most of these imperfect diamonds are used industrially.

The clarity grade of a diamond usually has a major impact on its value. This will vary based on the overall evaluation of the diamond and the different combination's of all attributing laboratory grades. Roughly speaking, a stone can vary by as much as 50% in value based on its clarity grade and on entire “finished product”. The clarity grade is usually a substantial factor in a stone's value; depending on a stone's clarity grade, all other factors being equal, the price can greatly fluctuate. All stones are created under similar conditions; however, in nature, each stone's growth, shape and clarity characteristics are formed differently. In fact, there are no two diamond crystals that are exactly identical. Similar to humans having their own fingerprints and DNA, all is different from diamond to diamond.


Carat weight is the actual weight of the diamond on a scale – it's not actually the size or the diameter of the stone. Round diamonds that are properly cut will usually have approximately the same “size” if they weigh the same. There are 100 “points” to a carat; a “fifty point” or 0.50 carat diamond is a half carat diamond.

It's all up to the consumer whether or not it’s more important to them to have a bigger diamond such as a big platinum engagement ring or a diamond with higher clarity. Usually consumers are concerned that the inclusions not be seen by the naked eye, only under magnification. Grades from SI2 up will provide this. The grades range higher and higher up to flawless, in increasing cost and consumers can determine what they want combined with other grading factors. At times, consumers want a stone with a “big look”, such as a big diamond platinum engagement ring and will not be concerned that an inclusion can be seen by the naked eye

Beauty is in the eye of the beholder - the important thing is that the consumer knows exactly what the grade is and what nature's birthmarks are like in the stone.

London Jewelers also offers an exceptional collection of loose 2kt diamond solitaire princess cut diamonds, as well as semi mounts for rings, and 2 carat loose diamond stones. London Jewelers will also trade-up original purchase of solitaires once the consumer’s diamond is reviewed by a gemologist and management on staff and approved for trade-up. Original Proof-of-Purchase and original certification document is required. Once the condition and value is substantiated and the stone is judged and authenticated by our gemologist and senior management, 100% of the amount will be utilized toward the consumer’s next diamond purchase, providing it is more than the original purchase. For diamonds NOT purchased at London Jewelers, the value will be determined by a London Jewelers gemologist and management and upon customer approval, may be applied toward the purchase of another diamond at London Jewelers. Should the consumer just wish to sell their diamond without making a purchase – once reviewed by prior method and approved an offer would be extended. Upon consumer approval, payment must be made by check.

If you are interested in engagement, or eternity rings you can check out our bridal category which offers selections from top brand names.

Please give us a call or visit any one of our locations for more details. If you also have any questions or comments about this guide, please don't hesitate to e-mail us your thoughts.

London Jewelers is a loose diamond specialist and an Authorized Jeweler for all brands listed. All of our items are 100% Authentic, brand new and in perfect condition. Items include the full manufacturer's warranty, certification. London Jewelers stands behind everything we sell 100%, as we have since 1926.