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.

G

G.I.A. - The Gemological Institute of America. A non-profit organization specializing in grading diamonds and gemstones. Known as the preeminent laboratory for impartial value grading.

Girdle - The narrow rim around a gemstone. The girdle is measured as the largest diameter of the stone.

Girdle width - The proportion of the girdle to the rest of the stone. Too thin a girdle leaves the stone susceptible to cracks and breakage, while a girdle too thick will have reduced brilliance and fire.

Gold - The most malleable of precious metals, gold will not corrode, tarnish or rust.

Gold filled - Any metal covered by a thin layer of gold. The layer must be at least 10k gold and 1/20th of the total weight of the piece.

Gold plate - Essentially the same as gold filled, except the gold content can be less than 1/20th the total weight.

Grade - The systems for valuing diamonds as compared to a master set of stones.

H

Half pearls - Unusually small pearls that have been cut in half to use for border decoration on jewelry pieces.

Head - The part of a jewelry setting that holds a solitaire stone. The head shape is determined by the shape of the stone, and the head size range is dependent on the size of the stone it must hold.

Heat treatments - Almost all rubies and sapphires on today's market have been heat treated for color enhancement. This is a permanent treatment, and therefore totally accepted in the trade.

Hue - The basic color of a colored stone. The pure color of the spectrum by which any variation in a given stone is judged.

I

I.G.L. - The Independent Gemological Laboratories Inc., recognized as a reputable resource for grading gemstones.

Inclusions - Any and all internal flaws naturally occurring in gemstones.

Irradiation - A treatment done on pearls and some colored stones for color enhancement that is not always permanent and must be stated on your bill of sale.

Irritant - The mother of pearl, or other substance, implanted into oysters in order to produce pearls.

K

Karat - The standard measure of gold purity wherein one karat is 1/24th pure, meaning 24 k gold is pure gold.

Knotted pearl strand - The knotting system for pearl strands that insures the pearls will not rub against one another. Such contact could chip and wear down the precious nacre.

L

Lab-grown stones - Any gemstone that is simulated in the lab using the same, or similar, properties found in the natural stones. These simulants are not considered imitations, but they are not natural.

Lacquer coating pearls - Used to create a lustrous shine, but it wears off quickly. Pearlessence, a fish-scale recipe, provides better luster and lasts a little longer. Both treatments should be fully disclosed.

Laser drill holes - Tiny holes drilled into diamonds with a laser beam to dissolve or chemically reduce black spots. The enhancement is permanent, therefore legitimate, but must be disclosed.

Loupe - The magnifying tool used to examine gemstones and jewelry. Typically to 10X magnification.

Luster - The deep inner glow that makes pearls uniquely beautiful. Luster is created by tiny crystals of nacre built up over the irritant. Natural pearls tend to have thicker nacre than cultured pearls, hence deeper luster.