Precious Metals | Yellow Gold jewelry

Pure Gold and Yellow Gold jewellery

Source: Australia, Argentina, Canada, Chile, India, Russia, South Africa, USA

Pure 24 carat gold is a highly malleable and soft metal with a deep yellow to orange-yellow color. Other colors of gold are created by alloying pure gold with other metals. Gold as a precious metal is a chemical element in the periodic table with the symbol Au (from the Latin word Aurum) and its atomic number 79.

Gold used in jewelry is measured in karats (k), with pure gold being 24 karat. 24 karat pure gold is always yellow in color. Pure gold is considered to be too soft for most jewelry so it is more commonly sold in lower measurements of 20k, 18k, and 14k. A lower "k" or "Carat" number indicates a higher percent of copper or silver mixed into the alloy. Copper is more commonly used than silver to dilute the concentration of pure 24k gold.

• 24k: 100% pure gold
• 18k: 75% pure gold, mixed with other alloys
• 14k: 58.3% pure gold, mixed with other alloys

Gold Metallurgy

The adjective "auric" refers to something made of gold. Gold does not react with most chemicals but can be attacked by corrosive agents such as aqua regia, chlorine, and fluorine. Due to its relative chemical inertness, gold is usually found as the native metal or alloy.

Occasionally large accumulations of native gold nuggets occur, but usually gold occurs as minute grains. These grains occur between mineral grain boundaries or as inclusions within minerals. Common gold associations are quartz, often as veins and sulfide minerals. The most common sulfide associations are pyrite, galena, stibnite and pyrrhotite.

Gold Distribution

Gold is widely distributed in the Earth's crust and can be broken into two categories:

Reef Gold: Hydrothermal ore deposits of gold occur in metamorphic rocks, igneous rocks (aka: "hard rock" or "sub-surface" mining).

Placer Gold: Known as "surface gold" found in alluvial or placer deposits.

Pure 24k Gold is a soft metal which has a hardness of 2.5 on the Mohs scale, with a Vickers Hardness (VHN or HV) of 140. Gold has a melting point of around 240º C.

Chemical composition: Noble Metal, Auric Chloride (AuCl₃), Chlorauric Acid (HAuCl₄)