Which Karat is Harder?  10K - 14K - 18K

     Many times I am asked, "What karat of gold is best?"  Or... At this other store I was told that 10K is best because it is harder and will last longer!  Or... Is it true that I shouldn't buy 18K because it is too soft?  Or... Should I always buy 14K because it is the best and never tarnishes?

      Let us first start with a statement.  Gold is gold, and it is as hard as it is!  But what one should consider is... What alloys are being used in the karated gold?  The three most common and abundant alloys we find in karated metals are silver, copper, and nickel.  There are other metals in small and trace amounts, but the average consumer has little if any knowledge of them.  Among the three metals, nickel is the toughest and also the hardest, followed by copper and last, silver.  Nickel is found in white gold only and has a profound bleaching effect when added to yellow gold even in small amounts, thereby having a significant effect on the color of the metal.

     Nickel aside, we are left with copper and silver.  With these two alloys, it is possible to make an 18K alloy as hard as a 10K alloy.  When you combine copper and silver in equal amounts and then add the alloy to gold, you end up with a karated metal that has very hard quality.  As you increase the silver content, the metal tends to become softer (in 18K) and greener in color.  I mention this because the average consumer in the United States tends to favor 18K gold that has a green tint over the deep yellow color that is favored in Japan.

     Let's look at some of the basic alloy percentages that are commonly used in the three karatages being discussed.  In 18K there are two popular blends, the first favored for color by the U.S. and the second by Japan.  The gold content is 75% in both.  The silver content in the first sample is 16.6% and the copper content is 8.4%.  The second sample has equal silver and copper contents of 12.5%.

     In the samples of 14K we have a pale yellow, with 25% silver and 16.6% copper.  When we reverse the alloy percentages, we receive a dark yellow color.  In the 10K alloys, we find one with the greatest popularity has a 11.5% silver, 40.3% copper and 6.5% zinc content.  Zinc is added to reduce oxidation during the melting of the metal.

     If we compare the wear hardness of the various karatages, we will find that the second 18K alloy, the first 14K alloy and the 10K alloy will have similar wear characteristics.