Gold is so rare that only an estimated 110,000 tons have been taken from the earth during all of recorded history. More steel is poured in one hour than gold has been poured since the beginning of time. Since it does not rust, tarnish, or corrode, gold virtually lasts forever. It is so soft and malleable that one ounce can be stretched into wire five miles long.
A karat is the measure of the actual amount of pure gold present. Pure or fine gold is 24 karats. But because of its softness and dense weight, gold is usually mixed or alloyed with other metals to improve hardness. Eighteen karat gold consists of 18 parts of pure gold mixed with 6 parts of other metals. Fourteen karat gold is 14 parts pure gold combined with 10 parts of other metals.10 parts of other metals.
Recent laws are very strict with regard to tolerances allowed for gold jewelry. The actual purity must be within 1/10 of a karat of the karat mark stamped into the jewelry. So 14K jewelry must be at least 13.9K. This is known as "plumb gold".
Colors of Gold
Pure gold is always yellow. But mixing gold with other metals not only increases its hardness, but also allows modifications in color. Alloys most commonly used in gold jewelry manufacturing are: copper, zinc, silver, nickel, and palladium.
How Alloys Affect Color
|Yellow Gold||Gold, Copper, Silver|
|White Gold||Gold, Nickel or Palladium, Zinc, Copper|
|Green Gold||Gold, Silver, Copper, Zinc|
|Pink Gold||Gold, Copper|
Gold jewelry can basically be manufactured using three different techniques: hand made, die struck, or cast.
The entire manufacturing process involves hand fabricating each part of the jewelry starting with a block of gold that is formed into wire, sheeting, tubing, and bars. These components are then shaped and assembled into finished jewelry using various tools by very skilled craftsmen.
Advantage – Intricate detail combined with one-of-a-kind appeal.
Disadvantage – It's the most costly of all processes.
Gold is rolled into thick slabs, tubes, and sheets and then struck by high pressure stamping machines. The high pressure compacts the gold molecules very tightly squeezing out all air, leaving very crisp and exact reproductions. All the coinage of the world's governments is produced by this method. Die struck jewelry, weight for weight, is the strongest and most durable of all the manufacturing processes. Many wedding bands and engagement rings are manufactured this way.
Advantage – Durability, no porosity, higher polish.
Disadvantage – Intricate designs are difficult to produce and equipment is large and costly.
Lost wax casting is a modern update on an ancient manufacturing process. A wax model is coated with plastic or rubber to make a hollow mold that captures every detail of the original design. Hot molten gold is poured into the mold. The wax evaporates, leaving a perfect gold replica.
Advantage – Lowest reproduction costs.
Disadvantage – Difficult to finely polish, potential for porosity (pitting) in the gold, less durable.
Gold has excellent working qualities that make it particularly desirable for fine jewelry. It is available in a wide range of finishes and styles to suit individual tastes.
- Appliqué – Soldering a design worked in gold to another piece of gold; soldering one color gold to another.
- Diamond cut – Sections of the surface are cut to achieve bright reflections.
- Enameling – Fusing colored glass or resins onto metal surfaces.
- Engraving – Cutting a design into the surface.
- Florentine – A criss-cross finish created by texturing the surface with a special tool.
- High-polish – Mirror-like.
- Milgraining – A detail that resembles a string of tiny beads applied as an ornamental border.
- Satin – Grained texture of satin cloth; has a softer shine than "high polish."
- Sand-blast or glass bead finish – A fine even-sanded texture applied with high air pressure in an enclosed chamber.