Gem Quality
Within each gemstone variety, quality dramatically affects price: a gem can sell for $100 or $2,000,000. When buying a gemstone - buy the best quality, most experts recommend. Choose a smaller stone of higher quality over a larger stone of lower quality, or buy a higher quality gem from an unusual variety if your budget is too small.
Well-known gemstones like rubies, emeralds and sapphires - which have been known for centuries - are more valuable than more recently discovered gemstones which are also beautiful and rare. You may be surprised how beautiful and affordable garnets, tourmalines, tanzanites, and other exotic gemstones can be.
Value factors: Color, Clarity, Cut and Carat Weight
Gemstone quality and value are evaluated according to the "four Cs": color, clarity, cut, and carat weight.
Color is the key factor. A common misperception in judging gems is people assume that the darker the color, the better the stone. That isn't true: color can be too dark, like some sapphires that look more black than blue. If a gem's color is too dark, it is subdued and lifeless. A much better rule of thumb is the brighter and more rich and vivid the color the better. In general, within each gemstone variety, a clear, medium-tone, very intense and saturated primary color is the most preferred. Muted colors or colors between hues, which you might find very attractive, are usually less expensive. Look at the color in different kinds of light.
The next most important factor affecting value is clarity, with clear transparent gemstones with no visible flaws being the most valued. Some gemstone varieties, notably emerald and red tourmaline, are very rare without inclusions of some kind so the price structure takes this into account.
Some gemstones are valued for their inclusions! Phenomenal gemstones owe their stars and eyes to inclusions. Tiny inclusions reflecting back light put the eye in cat's-eye chrysoberyl and the star in star sapphire. Inclusions can also be a birthmark, telling us where a particular gemstone was mined.
A good cut is something that may not cost more but can add or subtract a lot of beauty. A well-cut faceted gemstone reflects light back evenly across its surface area when held face up. If the stone is too deep and narrow, areas will be dark. If it is too shallow and wide, parts of the stone will be washed out and lifeless.
Gemstones are generally sold by weight, and not by size. The price will be per carat, which is one-fifth of a gram. Some gems are heavier than others so the same weight stone may be a different size! The carat weight also affects the price: large gemstones are more rare, so the price per carat is higher.
In general, gemstone pricing within each variety follows common sense: the more beautiful the gemstone, with the final visual effect of all the quality factors, the more valuable it is. Don't be afraid to choose what looks best to you!
The 4cs
Diamond Cut
The way a diamond is cut, its width, depth, roundness, size and position of the facets determine the brilliance of the stone. Even if the color and clarity are perfect, if the diamond is not cut to good proportions, it will be dull and less impressive to the eye.
Table: Flat, top facet of the diamond.Crown: Upper portion of the diamond, above the girdle.Girdle: Part that separates the top and bottom of the diamond. This is the widest part of the stone.Pavillion: Bottom portion of the diamond, below the girdle.Culet: The tip of the bottom of the diamond. This is the most fragile piece of the stone.Diameter: The widest part of the diamond as measured by the girdle width.Depth: Total height of the diamond measured from the table to the culet.
TABLE
The table of a diamond has a very important influence on the overall brilliance of the stone. The best cut diamonds have a table that is 56-62% of the size of the girdle diameter.
GIRDLE DIAMETER AND THICKNESS
The basis for checking the overall proportions of a diamond is the diameter of the girdle, the part that separates the top (crown) and bottom (pavillion) of the stone. All other measurements are related as a percentage of the girdle diameter.
Because very few round diamonds are absolutely round, the girdle diameter is measured in at least four directions, with the highest and lowest values reported on grading reports. You may see the Measurements section of a grading report look something like this: 5.44 - 5.46 x 5.75 mm. This means that the girdle is 5.46 mm at its widest point, and 5.44 mm at its least widest point. The third number represents the Depth of the diamond, which is the measurement from the top of the table to the culet.
PAVILION
The pavilion is the bottom portion of the diamond, below the girdle. The height of the pavilion greatly contributes to the diamond's overall brilliance. If the pavillion is too long or too shallow in proportion to the rest of the diamond, light will "leak" out from the bottom of the stone resulting in a duller looking diamond.
HOW DIAMOND CUT GRADE IS DETERMINED
The overall cut grade of a diamond is determined by taking into account all of the factors described above and plotting the results into a table. The table below shows the values used in determining the overall cut grade of a diamond. After each factor of the cut receives a grade, the overall cut of the diamond is determined by the lowest grade any of the factors received. For example, even if all measurements are ideal but the table size is only good, the overall cut grade of that diamond will only be good.
Diamond Color
The color of a diamond depends on the quantity and nature of trace elements within the stone and how these elements originated. Most commercially available diamonds range in color from colorless to pale yellowish. There are other colors of diamonds known as "fancy diamonds" which can be pink, blue, green, yellow, brown and even black.
The GIA (Gemological Institute of America) provides a letter scale in which diamonds are graded based on their color. The following diagram illustrates the range of color grades:
NOTE: The colors on this chart are for demostration purposes only. Since all monitors display colors diferrently, what you see on this chart may not represent the exact color grade.
Diamonds that are graded in the D-F range are the rarest and consequently most valuable. In reality, diamonds in the G-K range have such a small amount of color that the untrained eye can not see it and as such offer a great value. In order to provide our customers with the finest possible selection of inventory, you will not find any diamonds rated below P in color on the web site. Fancy color diamonds are available in their own section and do not follow the letter grading conventions in the chart above.
Fluorescence
This characteristic of a diamond causes a slight blue glow when the stone is exposed to intense, direct ultraviolet light. This type of light can typically be found in nightclubs. A small amount of ultraviolet light comes directly from the sun.There are differing opinions on fluorescence and whether to avoid it or not. We believe it comes down to a matter of personal taste and does not affect the value of the diamond.
Diamond Clarity
The process of the growth and creation of a diamond inside the earth does not occur evenly, but in several phases. In each phase, the conditions such as temperature, pressure and cooling are not the same and do not always remain constant. As a result, most diamonds contain what are called inclusions, internal features caused by the constantly changing conditions during different phases of the diamond's creation. These inclusions come in many forms including cloud-like features, fracture or tension cracks or even enclosed minerals that were present during the growth process of the diamond.
The GIA (Gemological Institute of America) has designated that clarity of diamonds is graded under the following guidelines:
FL:Diamond free from internal and external flaws under 10X magnification.IF:Absolutely free from internal faults under 10X magnification. May contain external features that should be so small that they can easily be removed by polishing.
VVS1:
Very, very small inclusions in the stone, very difficult to recognize under 10X magnification. These inclusions can not be in the field of the table.
VVS2:
Very, very small inclusions anywhere in the stone, only smallest external defects allowed.
VS1:
Only the smallest inclusions are allowable in the field of the table and only small faults elsewhere in the stone.
VS2:
Very small internal faults. Small external defects.
SI1:
Small internal faults, not visible to the naked eye.
SI2:
Small, easily seen inclusions under magnification in the table, but still not visible to the naked eye.
I1:
Inclusions easily seen under magnification, but difficult to see with the naked eye. Inclusions do not influence brilliance.
I2:
Large and numerous inclusions, just barely visible to the naked eye through the crown. Inclusions slightly diminish brilliance.
I3:
Large and numerous inclusions, easily visible to the naked eye, dimishing brilliance.
Clarity Enhancement
Now you can afford the largest, most beautiful diamond you've ever dreamed of - thanks to the Yehuda Clarity Enhancement Process.
This revolutionary process optically eliminates "feathers", which are naturally occurring feathers in most diamonds. The result is a more visually stunning diamond that you can purchase for significantly less than a similar-looking, non-enhanced diamond. Yehuda Diamonds are totally natural and the clarity enhancement is not visible to the naked eye. Only your jeweler will ever know that you own a Yehuda Clarity Enhanced Diamond.
Technically it works like this:
When light travels from one medium to another, it either changes its course or reflects in a different direction. When light attempts to pass through a non-enhanced diamond that has a feather, the light hits the feather and reflects off in any number of directions. That is why we see the feather and the diamond doesn't appear to be clean. With a Yehuda diamond, the light passes through the natural feather because the material used for the enhancement has the same optical characteristics as the diamond. The beam of light "thinks" it's still traveling through the same material (diamond) and continues its original course.
The amount of material used to fill the feather is so minute that the Gemological Institute of America (GIA) has reported that the clarity enhancement process ADDS NO WEIGHT to a diamond.
Carat Weight
The weight or overall size of a diamond is measured in carats. In fact, all gemstones are measured in this fashion. Of course, the larger the diamond, the more you can expect to pay for it, however the price does not increase on an even scale. A 2 carat diamond will not be twice the cost of a 1 carat diamond, despite being twice the size. The larger the diamond, the rarer it becomes and as such the price increases exponentially.
The chart below is a basic representation of the average sizes of diamonds for a particular carat weight. The chart is by no means exact and should only be used as a rough guideline and comparison.
When choosing a diamond for yourself or someone else, keep in mind that the same size diamond can look bigger depending on the type of setting it is mounted in. Also, a 1 carat stone will look bigger on a person with a size 5 finger, than it will on a person with a size 8 finger.
Round Brilliant
Princess
Emerald
Radiant
Oval
Pear Shape
Marquise
Heart
+1(714) 257-5519
Last updates OCT/05/2014 2:32 PM EST
© Copyright 1952-2014 by Al Adawy Jewellery INC. Al Adawy Jewellery is international Registed Trade Marke, All rights reserved to Al Adawy Jewellery INC