Tutorial

Learning about diamonds provides collectors with knowledge to make the best purchase for their budget and preferences. Understanding the language used with diamonds and gemstone jewelry helps to demystify the process. Here are some helpful terms.

Appraisal An evaluation of jewelry, gemstones or other valuables, expressed in dollars (or other monetary values) to be used for insurance, estate or other purposes. The appraisal is a researched estimate of retail replacement value, or for another appropriate market. A properly prepared appraisal conducted by a qualified appraiser affords protection in the event of loss or damage. It is critical for settling probate, estate and other types of property distributions.

Binocular Microscope A critical magnifying instrument in a professional laboratory. The gemological microscope has twin objectives & oculars which provides three dimensional viewing, various magnification lens, plus variable illumination sources to examine the exterior and interior of an object.

Branded Gemstone or Diamond A proprietary, often patented gemstone cut making the stone recognizable as a unique shape. Branded cut stones may also bear identifying laser inscriptions on the girdle (circumference).

Carat Weight A measure of weight, rather than the size of a gemstone or diamond as expressed by carats.

Certificate A written report describing the results of examination of a gemstone, diamond or other valuables detailing the weight, proportions, color and clarity grades, and any other variables pertaining to its identity and quality.

Clarity Grade A method of expressing relative levels of clarity in a diamond. Gemological Institute of America (GIA) has developed the most widely accepted grading scale ranging from highest, Flawless (FL) to Included 3rd level (I3), or lowest.
          GIA Clarity Grading: FL-IF-VVS1-VVS2-VS1-VS2-SI1-SI2-I1-I2-I3.

Color Grading Scale (GIA) Colorless diamonds are graded on a scale beginning with the letter D and continue to the end of the alphabet.

D-E-F	Colorless
G-H-I-J	Near Colorless
K-L-M	Faint Yellow
N O-P-Q R	Very Light Yellow
S-T-U -V-W-X-Y-Z	Light Yellow

Diamond A unique gem-mineral composed essentially of only one element: carbon. It is the hardest of all known natural substances ranking 10 on the Mohs scale. They occur in colorless forms, called "white" diamonds, but also occur naturally in a wide range of colors.

Dispersion The term used to express a transparent gem or diamond's ability to separate white light into the spectral colors; also referred to as fire.

Facet A polished surface placed on a diamond or gem.

Face-up Color Apparent color observed in a diamond or gem viewed in a direction perpendicular to the table or how it would appear in its setting.

Fancy Cut Any gemstone shape or cutting style other than a Round Brilliant cut. This includes pear, heart, emerald cut, marquise, princess, trillion, cushion etc.

Fire See Dispersion.

Flaw A catch-all term referring to any internal or external characteristics on a cut diamond or gemstone, also called imperfections or inclusions.

Flawless (Fl) A diamond or gem with no internal or external flaws or blemishes when viewed under 10X magnification.

Four Cs An easy to remember quality assessment for diamonds: Carat weight, Color, Clarity and Cut.

Hardness A relative ranking of a mineral's resistance to being scratched. The Mohs scale developed in the 19th century is the most accepted method for comparison of relative hardness. Diamond, the hardest known substance is rated 10 on the Mohs scale, and talc is the least hard mineral ranks 1 on the Mohs scale.

Imperfection Any internal or external flaw or blemish on a polished diamond or gemstone, also called an inclusion.

Karat A measure of gold purity or fineness, usually stamped on a piece of jewelry with the mark K or KT after a number. It represents the relationship of pure gold to the total metal alloy. 24K means pure gold. 14K equals 58.5% pure gold in the total metal.

Refraction This is how a gemstone handles light rays entering it, and is expressed in a stones' RI or Refractive Index.

Refractive Index (RI) A measurement of how light rays change direction (related to speed) as they enter or exit a gemstone.  There is a direct correlation between the higher RI's and a stones' brilliance.

Rough Diamond A diamond crystal in its natural state as found in the earth.

Slightly Included (SI) A clarity grade in a diamond, which shows more inclusions than VS but less than Included. Diamonds of this grade are usually very attractive to the naked (unaided) eye.