Harold The Jewellery Buyer spends his days working with gold. It is a passion for him. We thought that is would be interesting to do a series of posts on this blog to provide some interesting information on gold.
Gold is the most malleable and ductile of all metals. A single gram can be beaten into a sheet of 1 square meter, or an ounce into 300 square feet. Gold leaf can be beaten thin enough to become translucent. Gold readily creates alloys with many other metals. These alloys can be produced to modify the hardness and other metallurgical properties, or to create exotic colors. High quality pure metallic gold is tasteless and scentless. Gold is very dense, a cubic meter weighing 19,300 kg.
Pure metals are gray or silvery white but gold is yellow. Common colored gold alloys such as rose gold can be created by the addition of various amounts of copper and silver, as indicated in the triangular diagram above. Alloys containing palladium or nickel are also important in commercial jewelry as these produce white gold alloys. Less commonly, addition of manganese, aluminium, iron, indium and other elements can produce more unusual colors of gold for various applications.
Because of the softness of pure (24k) gold, it is usually alloyed with base metals for use in jewelry, altering its hardness and ductility, melting point, color and other properties. Eighteen-carat gold containing 25% copper is found in antique and Russian jewelry and has a distinct, though not dominant, copper cast, creating rose gold. Fourteen-carat gold-copper alloy is nearly identical in color to certain bronze alloys, and both may be used to produce police, as well as other, badges. Blue gold can be made by alloying with iron and purple gold can be made by alloying with aluminium, although rarely done except in specialized jewelry. Blue gold is more brittle and therefore more difficult to work with when making jewelry. Fourteen and eighteen carat gold alloys with silver alone appear greenish-yellow and are referred to as green gold. White gold alloys can be made with palladium or nickel. High-carat white gold alloys are far more resistant to corrosion than are either pure silver or sterling silver.
Harold The Jewellery Buyer 