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How to Determine 100% Pure Gold Without Assay

The purity of gold is measured karats, with 24 karats being the highest category. Countries such as the United States and Britain employ a hallmarking system to show that items of gold have been tested for purity, but it is quite common to come across foreign gold that has not been marked in this way. Although it is far more convenient for resale purposes to have an assay mark, it is possible to assay items yourself with a gold-testing kit you can buy online. A gold-testing kit will only enable you to test purity up to 91% (22 karats), so you will need an electronic tester to check for total purity.

Things You'll Need

Acid gold-testing kit
Electronic gold tester

Instructions

- 1
  Type the term "gold testing equipment" into your computer's search engine. This will bring up links to a variety of sites where gold testing kits are for sale. There are two kinds of gold testing equipment available. The most common and least expensive kind of testing equipment is a kit that consists of a number of vials of acid formulated to appropriate strengths to test for different widely-used purities of gold. The second kind of testing equipment is an electronic tester that gauges purity by measuring the conductivity of the metal. As of 2011, acid testing kits retail for as little as $50, while an electronic tester can cost as much as $1,000.
- 2
  Check your gold with an acid tester by applying a droplet of the strongest acid solution to the metal. Gold of high karatage won't react at all, while impure gold will result in an increasingly dark brown color, depending on the quantity of other alloys. The kit's accompanying instructions will explain the safety procedures you will need to follow. The kit will only test up to 91 percent purity (22 karats), but it should serve most of your needs because items made from pure gold are rare outside China, where they are used as traditional gifts.
- 3
  Perform the same test with an electronic tester by simply applying the probe to the metal and reading the digital meter. A good electronic tester will register up to 100% purity (24 karats), which is pure gold.

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