Introduction to Diamond Grading:  

"How do I pick my diamond?"

This Is a great question and one commonly asked by the engagement ring/diamond shopper.  Here, at William’s Jewelers we always show our center diamonds loose so they can be carefully inspected once you know what to look for. Lets start with Shape and then discuss "The 4 C’s," shall we?

SHAPE: Diamonds come in many different shapes.  You get to decide which one suits your eye and the ring design you choose.  I will discuss the more popular shapes and some of their characteristics below;

1. ROUND BRILLIANT, The most popular cut!!  It has been scientifically designed and re-designed through the decades for maximum brilliance, scintillation, and dispersion.  It is unmatched for its ability to evenly distribute light with no dark areas (extinction).
2. PRINCESS CUT: Also very popular.  This is essentially a square brilliant cut diamond.  Although square is preferred, rectangular princess cuts work well with some designs.  They tend to be a little deeper than round brilliant cut diamonds and therefore look a bit smaller.
3. MARQUISE BRILLIANT CUT:  Much less popular, but you decide if that’s good or not so good.  Some folks like a shape that is more unique and less often seen.  This is the diamond that has the outline of a football for lack of a better description.  Proper depth is important her to create enough brilliance.  They look bigger than the weight would indicate and special care needs to be taken by the diamond cutter to eliminate the bow-tie effect in the center.
4. OVAL AND PEAR BRILLIANT CUT: I lumped these two together because of similarities.  The oval has an oval outline (imagine that), and the pear has a tear drop outline.  Less common but still beautiful, these shapes work well with curvy and v-shaped designs.
5. HEART SHAPE BRILLIANT CUT: This one is shaped like a heart and is much less often seen, but can be exquisitely beautiful in the right design.  Also a relative bargain as far as price goes.
6. EMERALD CUT: This is where we depart from the “brilliant “ cutting style and go to a step cut.  There are parallel facets and cut corners on this rectangular shaped diamond.  They do have lots of  light return or brilliance but very little scintillation or sparkle as they are moved about.  This gives them quite a different overall appearance than the round brilliant and fancy brilliant cuts discussed above.

CHOICE: Obviously the shape of your diamond is your choice.  Here at William’s Jewelers we have a great selection of Rounds and fancies for your evaluation, and an unlimited supply of “available” diamonds from diamond centers around the world.  We have worked very hard to have a great JBT (jeweler’s board of trade) credit rating, which means we can buy from virtually any diamond broker in the world.  Something those with lower JBT ratings envy in a big way as you can imagine.

The four c’s speak to diamond quality as described in the GIA diamond grading system, which has been used worldwide for several decades.  The four c’s are CUT, COLOR, CLARITY, AND CARAT and I will attempt to briefly explain each.

CUT

In this context cut refers to how well the diamond cutter did his job, not the shape and name of the diamond cut.  A well cut diamond has tons of scintillation and dispersion ( fancy words for sparkle and colors) and no extinction ( dark areas).  Your eye is the best judge, but there are parameters that will put you in the right ballpark.  Sparkle comes from the triangular and kite shaped facets on the crown of the diamond.  The table is the flat, open, top of the diamond and doesn’t produce sparkle.  If the table is too big it crowds out the crown facets and diminishes sparkle.  A diamond that is very deep or shallow will allow light to escape from the sides ( pavilion) of the diamond which creates the dark areas, not good!.   The girdle or edge of the diamond should be medium to slightly thick.  A very thick girdle hides a lot of weight and you have a diamond that looks smaller than its weight would indicate.  The GIA cut grading scale goes as follows; poor, fair, good, very good, and excellent.  Obviously poor and fair should be avoided but anything good or above should be very pretty.  If you want something literally a cut above go for very good or excellent.

The GIA diamond-color grading scale assigns letter grades to color ranges commonly found in diamonds.  Yellow is the most common color in diamonds and its absence is a good thing.  Diamonds are graded in a white tray, upside down, against master stones of known color.  The scale goes from D to Z right down the alphabet and is broken into sections. DEF are considered colorless, GHIJ are near colorless, KLM are faint yellow, and NOPQR are very light yellow etc…..  If you go yellower than Z you have a fancy yellow diamond and the prices go up considerably.  What color do you want?  I have some suggestions.  In white gold or platinum mounting I recommend H color or higher so the diamond looks white against the white metal.  In a yellow gold mounting even J or K can look beautiful as long as the cut is good.

CLARITY

Clarity refers to the absence or presence of internal characteristics (inclusions, or flaws) in the diamond.  The size, color, and number of these characteristics, as viewed under a ten power stereo microscope with dark field illumination, determines the clarity grade.  The GIA clarity scale starts with F for flawless meaning no inclusions can be found with the grading microscope.  The next grade is IF for internally flawless meaning no inclusions can be found but there are surface irregularities.  Next is VVS for very very slightly imperfect and this and is further divided into VVS1 and VVS2 (one is slightly better than 2).  These inclusions are difficult to find under the microscope with a trained eye.  Next is VS for very slightly imperfect and this grade is also divided into 1 and 2 sub grades.  Inclusions are easier to find but still quite insignificant.  Then comes SI for slightly imperfect.  This is the grade most often seen in retail jewelry establishments.  Also subdivided into SI1 and SI2 but here is where the difference becomes more important.  An SI1 clarity means the inclusion(s) are easily seen under the mic but completely invisible to the unaided eye.  SI2 diamonds are considered eye clean, but in the right light a person with sharp vision may see something.  The last grade is I for imperfect.  By definition these diamonds have inclusions that are visible with the unaided eye.  This grade has sub grades of 1,2,3,…… but I wouldn’t go below I1.  Some I1 grades diamonds are quite beautiful and sometimes the inclusion is on the edge of the diamond and can be hidden by prongs or a bezel.  I like SI1 and SI2 clarities because of their "bang for the buck," but if you want better consider the VS grade.  VVS and IF are generally reserved for museum type pieces.  But, to each his own.

CARAT

Carat is a measure of weight.  The metric carat weighs .20 grams.  We tend to think of carat as a size measurement and if the cutting is good it works.  If the cutting is sub par you end up with a diamond that looks too large or small.  A too, large diamond is also too shallow and wont sparkle much.  A too small diamond has problems but probably wont sparkle much either.  You decide on the size of your diamond but consider this, the prices are not linear.  Prices are based on rarity so a one carat diamond could cost twice what a three quarter carat diamond costs.

Not one of the four c’s but I wanted to talk about it.  A well cut (GIA good or better),  reasonably white (H  color or better in white metal), and reasonably clean (SI2 or better) diamond will look awesome and stand up to the critical direct comparison with her “friend’s diamond “.

Again, not one of the four c’s, but why stop now? Some diamonds come with certificates from a laboratory that have the cut, color and clarity grades as stated by a trained grader (like myself, I have a GIA gemologist diploma).  The GIA reports are the most sought after and also the most expensive.  Expect to pay a premium for a GIA certed diamond.  The EGL (European Gemological Laboratory) is the most common as they are cheaper and just a little more lenient on grading.  Make sure the EGL cert is from EGL USA (weird huh?) as the others can be rubbish.  The certificate does not change what the diamond is, so if it looks great and has lots of life it could be the right one for you.

Come see us at William’s Jewelers and we can look at all of the things discussed here and make you into a diamond expert so you can make the right CHOICE!

MATT DENDEL
GERMOLOGIST, GIA

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