How to know the purity of my gold? what are ways to check gold purity? how does a jeweler know the purity of gold?

We are often asked "How do I find out the purity of my gold?" or "How do I test the quality of my gold?."   
Lets start with the basics:

1. We recommend leaving gold testing to the professionals.  Working with experienced professionals is far better than attempting to determine the purity and value of your gold.  That being said having some basic knowledge is always a good thing.
2. Look for a stamp.  Many times your jewelry will have a hallmark on it.  These hallmarks can tell a lot about a piece of jewelry just keep in mind they are not always accurate.  That being said they are a good starting place.  Take a look at the numbers on the piece.  Is it marked 583 or 585 or how about 14k or 14kt maybe even 14k hge.  There are lots of marks and they can be confusing.  As an example all of the previous marks indicate 14 karat gold except the last one 14k hge which indicated gold plating.  Another reason to just use the mark as a general guide.  You can read more about gold purities and markings in previous blog posts or in our educational section.

Here we discuss a few different methods used widely to test the purity of gold.  There are a number of different ways jewelers use to check the purity of gold.  

1. Hardstone (Hand Test):  This is the simplest gold purity test and fairly accurate as a good guideline, it is performed at most pawn shops and has been in use since ancient times. The central tool in the stone hand test is a touchstone (hence the name) which is usually a dark hard stone with a finely grained surface. When soft metals like gold are drawn across it, they leave a visible line. The color of the line varies with the purity of gold. By observing the color on the line, an experienced jeweler can tell the purity of gold. The one good thing is that it will give a good general idea and, to a very experienced user, can be pretty accurate!  To an inexperienced user however it can be misleading.  Knowing the qualifications of the buyer is quite important.
2. Fire Assay: This method known as 'fire assay' is the oldest known method of testing gold and continues to be one of the most accurate. To do this test gold is melted, a sample of the gold is taken, either by drilling through the poured bar or by capillary tube sampling while the gold is in a molten state. The sample is weighed very precisely and the weight recorded. All impurities and other metals are then extracted and removed, leaving just pure gold (generally .9995 or higher). The weight of pure gold is compared to the previous weight of gold and its purity is calculated accordingly.  Its a tried and true method and extremely accurate (probably the most accurate method).  This method is done by serious gold houses and refineries (like us) to ensure purity levels and accuracy.  The issue is that fire assay completely destroys the jewelry or coins in the process.  Additionally the equipment and knowledge to run this type of test is time consuming and costly to do so.  It generally makes sense for very large quantities of unusable items.  As usable items would be melted and not recognizable anymore
3. Digital Test:  Today there are certain machines that can test the purity of gold. These machines are "simple" to operate however they are not very accurate at all.  Most of the time they give out false readings and mislead users on purity.  
4. XRF Testing: X-RF Testing (X-Ray Fluorescence) is an excellent method to generate a complete analysis of gold samples, including purity and fineness.  X-RF machines determine results quickly as the X-ray assay takes only minutes to complete. This unique form of precious metal testing works by exciting the gold sample in X- rays. The metal then emits light (fluorescence) at an energy level specific to its atomic structure. By measuring this unique energy level, the X-RF machine accurately analyzes the purity of the sample.  These machines can also detect what type of other elements are in the metal and their percentages. X-RF can also be used to check the purity of any metal like silver or platinum making it diverse.  Another great thing is the X-RF method to test gold purity is nondestructive.  The problem is the X-RF machines to test gold purity are very expensive and cost prohibitive to purchase and maintenance cost is high.

Here at Velvet Box Society we use ALL of these methods in house and verify our materials in different ways based on subject matter. With the volatility in the price of gold and other precious metals, we cannot afford the time or the potential inaccuracies to not check every single piece.  So if you should have items you wish to sell we'd be happy to assist in the matter.  For more information contact us directly as we offer this service for dealers as well as the public!

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