Elements
Gold
Gold is a chemical element, atomic number 79. It has a melting temperature of 1947.52 degrees Fahrenheit (1064.18 degrees Celsius). It gains its abbreviation Au from the latin "aurum". It is used in electronics, dentistry and anywhere else its characteristics of light reflection, ductility and good general resistance to corrosion are desired.
It is the most commonly used element in making jewelry. It has been used since prehistoric times for ornamentation and may well have been the first metal man worked. Pure gold is very soft and usually alloyed to give pieces made from it strength and durability as well as to lower the cost.
Silver
Silver is a chemical element, atomic number 47. It has a melting temperature of 1475 degrees Fahrenheit (802 degrees Celsius). The chemical symbol Ag derives from the Latin "argentum",meaning white or shining. Silver is used extensively in photography, dentistry and nuclear industries as well as in jewelry and tableware.
Niobium
A chemical element, atomic number 41. Niobium, also abbreviated to Nb is also known (archaic usage) as Columbium.
This ductile gray metal is a member of the refractory family of metals, characterized by extraordinary resistance to heat and wear. With an atomic weight of 92.91 it is very close to the weight of gold.
It has a melt temperature of ( 4474 degrees Fahrenheit (2468 degrees Celsius) and cannot be soldered. Annealing and casting is possible only in an inert or high vacuum environment. Niobium is used extensively in the aerospace, medical,nuclear and automotive industries.
In jewelry use, niobium is prized for its ductility and colorability via anodizing. I use niobium over the more commonly known titanium because of the problems with removing titanium oxide. Upon exposure to oxygen titanium forms a very hard thick oxide layer which must be removed prior to anodizing. If it is not removed colors are dull and the higher voltage colors (teals, greens) are impossible to obtain. The process of removing titanium oxide is usually done with strong acids and as little exposure to oxygen as possible. Niobium needs a much gentler deoxidation process (stripping) that is more suitable to my workshop environment.
Nickel
A chemical element, atomic number 28. Nickel is abbreviated to Ni and a hard, ductile silvery-white metal that takes a high polish. It is also magnetic. Nickel in industry is used primarily as an alloying material to impart strength and corrosion resistance. In jewelry making, it is primarily used as an alloying material to make "white" or gray gold and is also used in making "surgical stainless steel", often used in pierced earring posts and wires. Nickel adds smoothness and permits a highly polished surface. Nickel is a known allergen, causing contact dermatitis in many people when worn over a period of time.
My jewelry contains no known nor any added nickel. If I am requested by a customer to produce something in white gold I use a non-nickel alloy in the process.
Rhodium
A chemical element, atomic number 45. A silvery-white metal, it is very hard and durable. The name comes from greek "rhodum", rose. It got the name due to its discoverer's experiments that isolated rhodium as rhodium(III)chloride, a red colored substance. It has high reflectance and does not react to oxygen. In industry it is primarily used as an alloying material to improve hardness and corrosion resistance and as a catalyst. In jewelry making it is used to elecroplate white gold alloys to provide a reflective white surface, more so than the alloyed gold would provide. It is also electroplated onto silver to retard tarnish. These electroplated coatings are usually very thin (measured in microns) and can wear off quickly. Rhodium used in this manner is harmless to humans. Rhodium is one of the most expensive elements available; an ounce costs about $9500. I do not plate any of my items with rhodium.