• No discussion about buying diamonds in any form is complete without discussing the classic "FOUR C's" of: Clarity, Color, Cut, and Carat weight.  Additionally, understanding such criteria as diamond grading reports and the factors effecting a diamond's cost (price) will also prove beneficial for increasing the buyer's confidence level that he or she is making a sound decision. 

• Clarity measures the relative visability of external blemishes or internal imperfections (inclusions) naturally occurring within a diamond as evaluated by a qualified gemologist. The clarity scale (GIA) is divided into six primary categories:

 

 

a.  Flawless (F or FL) - no discernable surface blemishes or inclusions visible when viewed at 10x magnification,

b.  Nearly Flawless (IF) - insignificant surface blemishes and no internal defects visible at 10x magnification,

c.  Very, Very Slightly included (VVS-1 & VVS-2) - extremely difficult to very difficult to find surface blemishes or minute inclusions at 10x magnification, but can be more readily seen at 10x once located at 20x magnification,

d.  Very Slightly included (VS-1 & VS-2) - difficult to somewhat easy to find surface blemishes or minor inclusions at 10x magnification,

e.  Slightly Included (SI-1 & SI-2) - easy to very easy to find surface blemishes or readily noticeable inclusions at 10x magnification, but will usually appear to be "eye clean" without magnification, though some stones will show slight inclusions when viewed from the side against a white background (note: GIA does not recognize an SI-3 clarity grade),

f.  Imperfect (I-1, I-2, I-3) - surface blemishes or obvious inclusions are somewhat difficult, easy, or very easy to find with the naked eye, especially after being located with 10x magnification.  I-2 inclusions effect either the diamond's aesthetic appearance (beauty) or durability (potential for cracking), I-3 inclusions effect both.

• The color scale is used to evaluate a diamond's internal tint and plays a significant factor in determining its price, colorless being the most desirable.  Color is best evaluated in natural light, as high intensity artificial lighting can make the diamond appear to be of a better color grade than it actually is.  Diamonds should also be examined for fluorescence, as blue photoluminescence will also make the diamond appear to be of a better color grade.  GIA Color grades range from:

 

 

a.  Colorless (D-F) - tint nearly undetectable to unaided, trained eye even when compared to white standard,

b.  Near Colorless (G-H) - tint almost undetectable to the trained eye, but apparent when compared to white standard,

c.  Near Colorless (I-J) - trace of tint just detectable to the trained eye, but noticeably apparent when compared to white standard,

d.  Faint Yellow to Faint Brown (K-M) - tint apparent to the trained eye and readily apparent when compared to white standard,

e.  Very Light Yellow to Very Light Brown (N-R) - tint is easily apparent to the unaided, trained eye, and

f.  Light Yellow to Light Brown (S-Z) - tint is obvious to the unaided, trained eye.

• Cut refers to the proportions and shape of the finished diamond, and is the most important element in determining how much light the diamond will reflect.  The finished diamond should be symmetrical. The table should be symmetrical, well-centered, and flat, not sloping. The cutlet should be centered when viewed from the top. The crown and pavilion facets should be properly aligned. And, the girdle should be perfectly round exhibiting a straight edge when viewed from the side. Ideally, the diamond should contain no extra facets, though extra facets may not have a significant adverse impact on its value depending on their shape and placement. From an aesthetic standpoint, a smaller, properly proportioned diamond is to be preferred over an improperly cut stone of greater carat weight and equal price. Acceptable feature proportions are calculated or expressed as a percentage of the diamond's girdle diameter. 

• Diamonds weights are measured in carats or fraction of carats called points, with 100 points equalling one carat or two-tenths (0.20) of a gram (i.e. 142, one-carat diamonds would weigh one (1) avoirdupois ounce). Diamond prices per carat weight increase exponentially as the average stone size gets larger given the same clarity and color grades. Stones under 0.30 carats or 30 points generally offer the most "glitterbang(TM)" for the money.

(1)  "Carat" is a unit of weight measurement used for weighing diamonds.  One carat equals 0.2 grams or 200 milligrams. 142 carats equals one (1) avoirdupois ounce.

(2)  "Point" is a unit of weight equal to 1/100 of a carat, 100 points equalling one carat, and written as 1.00 carat.

(3)  "Table" is the flat top surface of a cut diamond. Table diameter is considered acceptable when between 51.4-66.0% of the girdle's diameter.

(4)  "Crown" refers to the upper domed surface above the girdle of a cut diamond.  The angle of the crown between the girdle and the table is considered acceptable at between 30.0-37.0 degrees. Crown height is considered acceptable when between 11.0-16.2% of the girdle's diameter.

(5)  "Girdle" refers to the edge where the crown and pavilion of a cut diamond meet, marking the maximum diameter or width of the diamond. A girdle width of between 2.0-4.0% of the girdle's diameter is considered acceptable. Too sharp or thin a girdle increases the likelihood of chipping.

(6)  "Pavilion" is the tapered underhalf or base of a cut diamond below the girdle.  The angle of the pavillion from the girdle to the cutlet is considered acceptable when between 39.7-41.7 degrees. Pavilion depth is considered acceptable when between 41.5-45.5% of the girdle's diameter.

(7)  "Cutlet" is the end point of the pavilion, finer being considered better, however a sharp point is susceptable to chipping.

(8)  "Girdle Diameter" is the diameter of the diamond at the point where the crown and pavilion meet.  Other dimension characteristics of a cut diamond are expressed as a percentage (%) of the girdle diameter.

(9)  "Depth" is the vertical height of the diamond from the table to the cutlet.  Considered acceptable when between 57.0 to 65.0% of the girdle's diameter.

(10)  "Clarity" measures the degree of visability of surface blemishes or internal inclusions of a diamond.

(11)  "Color" measures the tint or internal color of a diamond, ranging from colorless to light brown or yellow.

(12)  "Cut" refers the shape (round, square, emerald, pear, oval, marquis, etc.) and proportions of a cut diamond.

(13)  "Brilliance" describes how well a diamond reflects white light.

(14)  "Included" refers to the internal defects of a diamond, appearing as ash like flakes, cracks, clouds, or other imperfections.

(15)  "Facets" are the small polished plane surfaces of a cut gem stone. A brilliant (round), full-cut diamond has 56 facets, while stones under 3 points can have as few as 16 (single cut).

(16)  "Eye Clean"  Diamond appears to be free of surface blemishes and inclusions to the naked eye. Diamonds graded SI-2 or better will appear to be eye clean.

(17)  "Cloud"  Minor inclusion appearing milky rather than dark or ash like, only minimally detracting from the stone's appearance.

(18)  "Blemish"  Imperfections found on the surface of a Diamond.

(19)  "Polish"  Describes the lustre of a diamond's exterior finish.

(20)  "TCW"  Stands for total carat weight of all stones comprising a piece of jewelry.

(21)  "TDCW"  Indicates the total diamond carat weight of the jewelry item.

(22)  "Fluorescence"  Refers to the emission of photoluminescence by a diamond detectable under a black light. Blue fluorescence can enhance a diamonds color, but other colors are considered less desireable.

(23)  "Symmetry"  Describes if the diamond is true to its desired shape and is in balanced proportions.

(24)  "Make"  Describes the diamond's cut and proportions.

(25)  "Fire"  Describes the intensity and diversity of the light spectrum (rainbow colors) emanating from a diamond.

(26)  "Finish"  Refers to the quality of the diamond's polish and symmetry.