Every piece of jewelry is shaped in a different way. The design is different, the shape is different (ring, earring, pendant, etc.), the finish of the metal is different and the opacity of the gemstone is different.\ Only experience can dictate the best way to light and set up a particular piece of jewelry. Attention to detail is crucial and the ability to control the elements is what creates a good final image.
Experience is knowledge acquired over time. It's knowing exactly what to do with a piece of jewelry....knowing how to style it; knowing the best lighting to use with a colored stone mounted in a yellow gold ring; or knowing how to get the most detail from a diamond by controlling color, light intensity and the direction of light.
The lighting set-up is the most important component in jewelry photography and is the product of professional experience. Jewelry is highly reflective and when photographing it you naturally capture the surrounding area in the surface of the jewelry. With skill and properly positioned lighting unwanted reflections can be minimized or avoided completely. Also, every piece of jewelry is different so each piece presents new challenges and rules on the set-up table. For example, a ring with an opal stone requires different lighting than a necklace with diamonds, or a pendant with onyx, or earrings with emeralds, and so on. There is no "one-for-all" lighting set-up when photographing jewelry.