How to Assay Gold

1.  Decide whether you intend to perform a qualitative or quantitative assay of your gold.

  • The quantitative method is the most often used method to assay pure gold as it is important to determine the weight or amount of gold to consider the true overall worth.
  • The qualitative method of gold assay is equally as important as quantitative though, because it helps you to determine the purity of the gold you intend to assay.

2. Determine the best way to perform the type of assay required to reach your end goal. You can perform a fire assay or Aqua Regia technique.

  • Fire assay involves taking a small sample of the metal and wrapping it in lead foil with addedsilver and cupelling it in a furnace and it removes all other base metals. When you mix the sample with a fluxing agent, fuse it at a high temperature and reduce it, the mixture will then cool leaving the agent at the bottom of the furnace.
  • You can employ the more accurate Aqua Regia technique at lower levels which will enable you to test more elements of your sample at once.

3. Complete a simple assay technique that involves using an Iodine solution to dissolve fine gold from the other minerals contained in your sample if you want to mine gold from ore.

4. Omit the cupellation stage and melt your gold sample with silver and press it into a thin sheet. Then, dissolve the other base metals with nitric acid and commence weighing your gold.

5. Add additional materials to produce a chemical reaction and determine how much gold exists in your sample. Depending on the added chemical you use, your sample will turn a range of colors that will indicate the level of purity.

6. Hallmark the sample to set its value. This quality control process includes applying a unified standard of symbols to determine and declare the value of your gold sample.

  • Seek out a professional consultant to perform this quality control process as you need the opinion of a certified and unbiased third party to ensure accuracy and validity.

7. The method described above is the classic method used by professionals for years however it is rapidly being replaced by non destructive hand held x-ray technology.


  • You will need several materials and more than a basic understanding of chemistry to perform the process to determine the amount of gold in your sample by way of colorizing the metal.
  • It is important in fire assay to wrap the sample in aluminum (or other approved material) to eliminate the possibility of contamination.
  • Laboratories that perform gold assay consider the fire assay method the most preferred technique.
  • Prior to performing your own assay, research the process thoroughly, consult professionals and viewphotos of the process to get perspective on the intensity and outcome of testing.

Sources and Citations






This page was last modified 18:25, 25 April 2011 by Jack Herrick. Based on work by WRM, Übersetzungen, traduce, BR and Jack Herrick, also Jewelking and Pranit and Anonymous.

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