Back to our main page: engagment rings guide

D

Depth - The distance from a gemstones table, top, to culet, bottom.

Depth percentage - The measurement of a gemstone's depth (top to bottom) in relation to its diameter (width of girdle). The importance of this relationship cannot be overstated, as it is responsible for refraction of light, hence, the brilliance and fire that a gemstone can display.

Dispersion - Or "fire", the rainbow colors seen in a properly cut gemstone.

E

E.G.L. - European Gemological Laboratory. An internationally respected organization that provides independent quality grading for diamonds.

Emerald cut - A step cut gemstone that can be rectangular, square, or even Triangular, where the corners have been cut off for protection and easier prong setting.

Enhancements - The only enhancements that are accepted in the gemstone industry are those that result in permanent color improvement. All enhancements should be clearly stated on the bill of sale. External reflection - Although the main source of fire and brilliance of a diamond is found in the facets, but the polish is also responsible for reflection of light and is called external reflection.

Extinction - Dark or black spots in a colored stone.

Eye-clean - A gemstone where the flaws cannot be seen without a 10-power loupe.

F

Faceted girdle - A girdle that has been cut with facets.

Facets - The flat, polished, cut surfaces or planes of a gemstone. Each cut is made with the proportion of the entire stone in mind.

Fancy color diamonds - Any color diamond other than yellow, brown or gray.

Fancy shapes - Any gemstone shape other than round, also called fancies.

Fancy yellow - Diamonds in the D to Z colorless category that are so yellow that they transcend the scale and become a classification all to them selves. When bright yellow, they can be as valuable as D colorless diamonds.

Feathers - An internal flaw (inclusion) in gemstones that can begin on the surface of the stone and work deep inside. They can either add character, or destroy value, depending on how much they block color uniformity and threaten durability.

Fineness - The purity of gold is described by parts per thousand, or by the karat. The purer the gold, the higher the fineness. 24 k gold is pure and has a 999 fineness stamp.

Fingerprints - A type of inclusion (internal flaw) particularly found in corundum. Finish - The term for describing the quality of polish, proportion of cut, and overall appearance of a gemstone.

Fluorescence - When exposed to ultraviolet light, about half of all diamonds will display fluorescence. The amount of fluorescence determines the level to which it effects value. Fluorescence is graded from None to Extreme, with several steps in between, and it will be indicated on the stone's certificate.

Foil backing - A method of color enhancement for colored stones that is rarely practiced anymore. Care should be taken when shopping for antique rings or jewelry with a closed back setting.

Fractures fillings - In diamonds, fracture filling entails a molten glass filling that improves clarity. You can get a lot more stone for your money buying fracture filled diamonds, the problem is that the treatment isn't always permanent. For emeralds, fracture filling is done with oil or epoxy. Again the advantages and disadvantages are the same as with diamonds. Get all enhancements clearly stated on your bill of sale.

Fractures - Or cracks, sometimes called feathers. Typical in many gemstones, including diamonds and are usually nothing to worry about.

Fresh-water pearls - Pearls produced, either naturally or cultured, in fresh water.

Full cut - A gemstone with 58 facets.