WHAT TO LOOK FOR IN PRONG-SET JEWELRY

A common misconception in judging the quality of a piece of jewelry with prong-set gemstones is that a large amount of metal covering the gemstone is desirable. While the amount of metal covering a gemstone is important to longevity, a much more significant -- and often overlooked -- measure of quality is the condition of the gemstone's seating.

When a gem is prong-set, part of each prong is carved out to make a resting place -- a seat -- for the gemstone. Once the gem is in place, the prong is hammered, or pressed, over the top of the gemstones, keeping the gem snugly in place.

When a prong's seat is well-cut, the prong's thickness at the seat is never less than one-third and never more than one-half the depth of the cut for the seat. If the seat for the gemstone is cut too deeply -- more than half the depth of the prong -- the tip can easily be lifted up and potentially break off.

	In a quality prong setting, the prong's thickness is never less than 1/3 and never more than 1/2 the depth of the cut for the seat.
	When a seat if cut too deeply -- more than half the depth of the prong -- the tip of the prong is prone to lifting off the gemstone and breaking.

Gemstone seats that are cut too deeply are the number one reason for prong failure.

Metal extending over a gemstone may give the illusion of a secure setting, but cannot compensate for weakened prongs resulting from a deeply cut seat. Excess metal over the edges of gemstone only serves to hide a gem's beauty.

	In a setting where excess metal covers a gemstone, the setting may only appear to be secure.
	Another problem to watch out for in a prong-setting is an ill-fitting gemstone seat. When a seat is poorly cut, the gemstones facets and edges do not fit snugly into the seat, resulting in loose gems and potential loss.

A poorly cut gemstone seat may cause loose gemstones.

Because gold is a malleable metal, the tips of prongs - the part of the prong which extends over the gemstone - do wear away over time. Retipping prongs is occasionally necessary to replace the metal that has been worn away.

The best way to find out whether it is time to have your prongs retipped is to bring your jewelry to a reputable jeweler for cleaning and inspection every six months. A good rule of thumb, though, is that if the thickness of the metal covering your gemstone is less than or equal to the thickness of three sheets of paper, you ought to have your prongs retipped.

When the height of the prong tip is less than or equal to three sheets of paper retipping is needed.