How to Understand Karat Gold Purity

How to Understand Karat Gold Purity


The purity of gold is measured in karats ("k" or "kt"). The number of karats represents the purity of the gold in a specific item. For example a 24 karat gold item will be the purest at 99.999% gold or all 24 parts pure gold. 18 karat gold is 75.00% pure gold or 18 parts of 24 parts pure gold.The remaining six parts are made up from other metal alloys to harden the gold and brighten and or change the final gold color. 14 karat gold is 58.5% pure gold or 14 parts of 24 parts pure gold. 10 karat gold is 41.66% pure gold or 10 parts of 24 parts pure gold. 24 karat gold is the softest form with hardness increasing as the karat gold content decreases and the accompanying alloy component increases. In the jewelry industry it is common to refer to 10 karat as a metal that contains gold as opposed to karat gold as the final product is less than 50% pure gold.

Karat Gold Alloy

In its natural state gold is a rich yellow in color. As the karat content decreases the color and strength of gold can be altered through the addition of alloys. 18 karat gold is 75% fine gold alloyed with 25% copper, silver, zinc and other alloys. The combination of metals in 18 karat makes a strong durable alloy allowing the rich gold color of higher karat items.14 karat is 58.5% fine gold alloyed with 41.5% copper, silver, zinc and other alloys. 14 karat is stronger than 18 karat gold because of the alloys however pales in the rich gold color of 18 karat. 14 karat is most popular in North America.

White Gold Alloy

18 karat white gold is 75% pure gold with 25% nickel, fine silver and other alloys. It is difficult to completely camouflage the rich yellow-orange color of fine gold with only 25% alloy. White alloy has a deep gray and yellowish tint. 18 karat white gold jewelry is rhodium plated adding a bright silver-white chrome color. 14 karat white gold is 58.5% pure gold alloyed with nickel fine silver and other ingredients. This alloy is bright gray color and much harder than 18 karat gold. Rhodium plating of 14 karat items makes the final product a bright silver-white chrome color.

Other Gold Colors

Other gold colors red, pink and green are produced by altering the formulas and specific metals of the alloy. These colors are fairly rare in the sense that client demand is limited but not more expensive than white and yellow primary gold colors.

Metals and their Alloys

When choosing a karat gold one must consider their different properties. Metals differ in terms of durability, malleability, and hardness. Some metals are also more reactive than others which means the metal will react to the atmosphere and your body's pH. Reacting with atmosphere can cause undesirable discoloring of the metal. When your skin reacts to the metal's alloy you may see a black coloring allergic reaction. People with allergies to metals are usually just allergic to copper or nickel which can be avoided using a different formula for the alloy.

5 Tips on Mountings

Five tips to consider when choosing which karat gold for a particular type of product application.

  1. If you are considering a channel set mounting 18 karat may be too soft to hold the channel set diamonds correctly, 18 karat being softer metal and having a higher rate of deterioration through normal wear.
  2. Another example would be a four prong Solitaire mounting using a 14 karat prong head set in 18 karat ring mounting. The reason for this is 14 karat is much stronger than 18 karat for this application.
  3. Mountings that measure under 2 1/2 mm on the shank are technically considered thin and should be manufactured using no higher than 14 karat gold.
  4. From time to time designers in  the jewelry industry establish designs and trends attempting to separating their products from the crowd. Unfortunately some of these ideas should be discarded at the design studio before production is ever considered. An example is the tension mountings! It is counter intuitive to believe the integrity required to properly secure an expensive diamond in any form of tension mounting is possible. The mere design dictates diamond security is violated no matter what karat gold content.
  5. Micro pavé, the setting in the mounting by drilling a hole in the mounting where this diamond is to be set and using a hand engraver to pulling metal up over the diamond is probably better accomplished in 14 karat as 18 karat maybe too soft of metal for the tiny prongs in normal wear.

It is import and to understand that all gold mountings have life expectancy of 10 to 15 years. Normal wear and tear on prongs and ring shanks requires annual inspection to ensure diamonds do not become loose and potential loss.

Rule of Thumb :If you insist on using18 karat gold for mounting that have thin profiles, narrow prongs, thin shanks,small channel set environment, micro pavé with important diamonds, make sure you have great insurance coverage!

Frank Fisher

Author: Frank Fisher

Frank Fisher (Sasha Evdakov) started learning about diamonds at a young age through his cultural background and family influence. He spent years being mentored by the best diamond dealers and has been studying diamonds and the diamond market since 1998.