Diamond 4 C's
The famous 4 C's of a diamond are the most significant grading parameters of natural diamonds and together determine most of the diamond's value. Considering the importance of the 4 C's, they should always be graded independently by a professional laboratory such as TIG, to ensure impartial and accurate grading.
The carat weight of a diamond affects the size of a diamond, together with the shape and cut. Every stone analyzed by TIG is weighed using precision scales in a controlled environment. Measured to the nearest 1/100th of a carat. 5 carat = 1 gram.
The cut grade can greatly affect the face-up size and appearance of the stone, especially when a very deep or very shallow cut. More importantly, the cut of a diamond is the single most important factor when considering the brilliance and scintillation of a diamond. Laser technology measures the exact measurements and angles of every facet of the stone and after an additional visual inspection by the gemologist as well as tools measuring the brilliance, fire and scintillation of the stone, a cut grade from Ideal to Poor is determined.
Round brilliant diamonds are also inspected for 'hearts and arrows', a unique attribute found in premium and ideal cut round diamonds.
White diamonds are graded from D (completely colorless) to Z (significantly tinted yellow or brown). Every diamond sent to TIG is graded using a master set of diamonds to ensure accurate and consistent grading throughout.
The clarity grade of a diamond represents the size, location and type of natural imperfections in the diamond and whether visible at 40x magnification, 10x magnification or at the 'naked-eye' view. Such imperfections can be internal or external blemishes, clouds, feathers, carbon spots, pin points knots and more. Based on extensive training and experience, two separate gemologists grade the diamond using all three views to determine the clarity grade of the diamond. In the case of a discrepancy, a third gemologist will inspect the stone and the majority grading will decide. Clarity is graded from Flawless (FL) to Visibly imperfect I3.
Additional Diamond Specifications
The diamond's polish refers to how smooth the surface of the diamond is. Polish is graded from Excellent, Very Good, Good, Fair to Poor.
The symmetry of the diamond refers to both the outer shape and measurements of the stone (eg. how perfectly round a round diamond is) as well as the alignment of the facets. Symmetry is graded from Excellent, Very Good, Good, Fair to Poor.
Fluorescence is a common property found in approximately one third of all polished diamonds. Fluorescence is the visible glowing light - usually blue - that some diamonds emit when exposed to ultra-violet (UV) light. Diamonds are graded from Very Strong, Strong, Medium, Faint to None depending on the intensity of this light.
For the vast majority of diamonds, the fluorescence will not affect the appearance of the stone at all and in most cases of Medium to Very Strong fluorescence, people tend to prefer the icy blue look that makes the diamond appear up to two shades whiter. In extremely rare cases (less than 0.2%), Strong to Very Strong fluorescent diamonds appear hazy or milky and so it is recommended to inspect such diamonds carefully before purchase.
The thickness of the furthest edge or side facet of the diamond, usually the place where the diamond is set in jewelry. Girdles come very thin to very thick and can either be smooth or faceted. A smooth girdle may improve the face-up color of the diamond whereas a faceted girdle will look more appealing when viewing the diamond from the side.
Depth refers to the total depth percentage of the stone. Depth is calculated by dividing the mm depth of the stone (from the table to the point or culet) by the average of the width and height of the outline of the stone.
The largest facet of a diamond, the table is the top facing highest point of the diamond. Measured as the percentage of the entire outline of the stone (width and length), measured from the girdle.
Usually the smallest or non-existent facet of a diamond and the lowest point at the bottom of the stone.
Metals & Stamps
Hallmarking or inscribing a stamp on precious metals is standard practice worldwide and is required in many countries. There are wide ranging types of hallmarks and stamps, indicating the time period, origin and type of metal, as well as its purity. The standard and popular engravings for gold, platinum and silver are as follows:
Silver stamped with '925' has a purity of 92.5% silver and 7.5% additional white metals. This is the standard for silver jewelry and is also known as 'Sterling Silver'.
'9K' or '375' Gold
9 karat gold is made of 9 out of 24 parts pure gold and 15 parts additional metals or 37.5% purity. These additional metals will determine whether the color of the gold alloy is yellow, white, rose or other. As pure gold is a soft metal, 9K gold is harder than the finer options, however will tend to have a lower quality finish, higher porosity and lighter overall weight.
'14K' or '585' Gold
14 karat gold is made of 14 out of 24 parts pure gold and 10 parts additional metals or 58.5% purity. 14K gold is slightly harder than 18K gold and higher purity together with a high quality finish. Overall weight is slightly lighter than 18K however in most cases will have the same appearance. 14K is popular with engagement jewelry, particularly in the US.
'18K' or '750' Gold
18 karat gold is made of 18 out of 24 parts pure gold and 6 parts additional metals or 75.0% purity. 18K gold has the perfect balance between strength and a fine and pure finish. 18K is the standard for fine gold jewelry in the Australia, UK, Italy and other parts of Europe and Asia.
Platinum is casted in very high purity and as it's a higher density metal, it is significantly heavier than gold and silver. Platinum is usually made in 90%, 95%, 98% and 99% purity, stamped '900', '950', '980' or '990' respectively. Without specifying the exact purity, platinum is often simply stamped 'Pt' or 'Plat'.