Gold Testing: How to Tell What Karat Your Gold Is

Updated on November 11, 2018
Beth Eaglescliffe profile image

Science graduate and business advisor, health educator and author, Beth writes on a wide variety of subjects.

How to Determine the Karat Level in Gold

  1. Look at the color. The deeper the orange-yellow color, the higher the karat.
  2. Check the hallmark. Are the assay marks clear and are they from a country you can trust?
  3. Carry out an assay test. Take care. Wear protective clothing as you will be handling acid.

Genuine heirloom or worthless replica? A gold assay test will reveal the truth.
Genuine heirloom or worthless replica? A gold assay test will reveal the truth. | Source

Test the Karat of Your Gold at Home

The only way to determine for sure an object’s karat value is to carry out an assay test. All jewelers and gold dealers will use an assay test kit before they purchase a gold item.

The kit consists of a number of different solutions of dilute acid and a touchstone. The touchstone is made of a dark acid-resistant rock such as slate. The jeweler rubs the gold object gently across the stone so that it leaves a streak mark. He or she then applies the acid solutions in turn to the mark. The higher the gold content of the metal, the less of it will vanish when acid is applied.

These chemical kits can be bought on-line for home use if you want to check the karat of your own gold items. I use the Puritest Acid Gold Jewelry Test Kit with scratch stone. The kit consists of six small bottles of acid (one for each type of metal to be tested), a scraper tool and a testing stone. The video below shows how simple the test is to carry out.

How to Test Gold Karat Using Assay Chemicals and Touchstone

Assay Marks and Hallmarks

"Assay" means “a test." A gold assay test shows the percentage of gold in relation to other metals in an item. It is a test of value rather than of quality. Expensive materials can be poorly manufactured and, similarly, cheaper metals may have been worked with exquisite craftsmanship. An assay or hallmark is an objective chemical test. Deciding the quality of an object is subjective.

Hallmarks show that an assay test has been carried out on the gold object to confirm its karat rating. The reliability of the hallmark depends upon the country of origin. State-controlled assay offices imprint a mark onto the gold showing the year and place of assay together with the percentage of gold found, or the karat rating. The hallmark is very small so you may need a magnifying glass or jeweler's loupe to see it clearly.

If the hallmark is clear and easily readable, this is the quickest way to check the gold content of an item. However, over time some of these marks can become worn, and some may have been deliberately tampered with. So how do dealers determine how much a gold item is worth if the karat mark is indistinct or missing? There are several ways to do this, as explained below.

Assay tool kit with touchstone and acid vials. Used to test the karat rating of precious metals.
Assay tool kit with touchstone and acid vials. Used to test the karat rating of precious metals. | Source

Differences Between Fake and Real Gold

 
Real Gold Item
Fake Gold Item
Hallmark
Should clearly show the year and location of the assay test center. Consult reference books to confirm that you have a genuine hallmark.
Hallmark may be illegible or missing.
Weight
Gold is heavy. You can feel the weight of it in your hand.
Be suspicious if the object is lightweight. Gold-plated items may fool you by looking like solid gold until you judge their weight.
Price
Compare prices before buying so that you have a good idea of the correct market value.
Remember the old adage. "If the price sounds too good to be true, then it probably is."
Malleability
Pure gold is a very soft metal and will dent easily.
A gold-plated item will be harder because the gold is just a thin coating over a tougher base metal.
Acid Test
Gold does not react with nitric acid.
A lesser metal will foam or dissolve when a drop of nitric acid is applied.

Karat Is a Measure of the Purity and Value of Gold

The value of gold is determined by its fineness or karat rating. An object made from 18-karat gold will cost you more than the same object made from 9-karat gold. An experienced jeweler will often be able to guess the value of an item just by looking at it, but they also carry out tests to determine the karat rating of gold. Knowing how a jeweler determines the karat value will help you, should you ever be buying or selling gold.

Karat (spelled "carat" in the UK) is a measure of the fineness and quality of gold. That is, the amount of gold relative to other metals that make up an object. In US and Canada, the most frequently used karat values are 14 karat and 18 karat (meaning 58.5% and 75% gold respectively). In UK, 9, 18 and 24 carat gold are the most frequently used alloys.

The higher the karat value, the greater the proportion of actual gold metal in your object. For example, an 18 karat gold ring will be made from 75% pure gold and 25% base metal (or alloy). A 9 karat gold ring will contain only 37.5% pure gold.

What Acid is Used in Gold Testing Kits?

Nitric acid is used to test the purity of gold objects. Gold is the only metal that is dissolved by this acid. A tiny scrape of the gold item is placed on a touchstone. Nitric acid reacts when brushed onto real gold and you will see fizzing if your gold jewlelry is genuine.

A retail metal testing kit (I recommend a good one in the first paragraph of this article) consists of several different strengths of acid solution. The different levels of nitric acid enable you to test for different karat numbers.

The gold hallmark shows the karat rating. Here it is inside the scissor handle.
The gold hallmark shows the karat rating. Here it is inside the scissor handle. | Source

How to Tell if Gold is Real or Fake

If you don’t want to do the acid test described above there are other ways to tell if your gold is real. However, they are not as easy to do and may not give such a clear result. The video below describes a few of them.

Indicators that show whether your coin or jewelry is pure gold or fake.

  1. Its weight will show if it has been adulterated with a lesser metal.
  2. Pure gold or silver has a distinct acoustic signature. This can be tested using an app or by using a special acoustic verifying machine.
  3. A magnet will reveal if there is any iron present in the metal. Gold is not attracted to a magnet.

4 Easy Tests to Spot Fake Gold or Silver

How Do Jewelers Test Gold and Why Do You Often Only Get Scrap Value?

Jewelers are shrewd business people. The value of gold fluctuates from day to day. Their ability to accurately assess the value of gold items is essential for them to turn a profit. Their offer to you will be related to the price they can achieve when selling on the item. They use science (objective) and experience (subjective) to test gold.

  1. They will examine your gold trinket using a loupe magnifying glass. A loupe enables the fine detail of hallmarks to be read. The jeweler will check the authenticity of the hallmark and feel the weight of the item.
  2. Using acid and a touchstone, they will check the karat value of the metal. The chemical reaction of nitric acid on gold demonstrates the alloy content of the object.
  3. If the jeweler is satisfied with the result thus far, he will look at the quality of workmanship and the integrity of the item. If it is badly damaged, or of poor (tourist) quality, you are unlikely to be offered any more than scrap value.

Bars of gold are an investment vehicle by themselves and turning them into jewelry often does not increase its commercial value. The resale value of secondhand gold jewelry depends on supply and demand and there may be little demand for old-fashioned or dated pieces. Unless an item is individually crafted and of exquisite quality, second-hand values are low as the jeweler will simply be selling them on to be melted down into gold ingots for investors.

Gold bullion. This gold bar weighs 12.5 kilograms ( 27.5 pounds) and is worth about US $500,000 (April 2018.)
Gold bullion. This gold bar weighs 12.5 kilograms ( 27.5 pounds) and is worth about US $500,000 (April 2018.) | Source

Gold Is Inert

  • One of the reasons why gold is such a prized metal is that it is chemically inert. This means it does not react with air. Gold does not oxidize (i.e. rust) like many other metals.
  • Gold also does not cause skin irritation if worn as jewelry. Discoloration or rashes on the skin next to the jewelry indicate that the gold has been adulterated with a base metal.

Can Vinegar be Used To Test Gold?

Vinegar (ascetic acid) can be used to clean some metals. It is not really a testing fluid, it is more of a cleaning agent. If you rub an object made of pure gold with neat vinegar it will remove marks and leave your jewelry shiny and clean. However, if the metal is not real gold, the acid will cause pitting (small holes) on the surface and your ring or bracelet will be damaged.

  1. Pour some white vinegar into a glass container. Do not dilute with water.
  2. Place your gold item into the liquid and leave for 15 minutes.
  3. Remove your gold pieces and rinse well in clean water.

Gold Varies in Color From White to Red

There are many variations in the color of gold, ranging from white through to deepest red. Pure gold is a deep golden yellow orange. In its purest state it is very soft and although this makes it very easy to work with, for everyday use a harder metal is needed. Pure gold is therefore combined with a cheaper base metal to form an alloy.

Copper or silver are commonly used in combination with gold to strengthen it. Thus what is commonly referred to as white gold has a high proportion of silver in the alloy. Similarly red gold contains a lot of copper in the alloy.

The color of gold depends on the amount and type of alloy metal used.
The color of gold depends on the amount and type of alloy metal used. | Source

What is Gold Worth at Today's Prices?

The value of gold bullion fluctuates according to supply and demand. If there are a lot of people chasing a small amount, the price of gold rises. If mining companies increase output and flood the international market, the price falls. Gold is seen as a safe haven investment. Governments as well as individuals invest in gold as a hedge against economic uncertainty.

This variability in demand means it is impossible for me to quote an accurate "spot" price. From the time of you starting to read this article to when you have finished it the value of gold could have changed by as much as 5% or 10%.

You can search the internet for websites that give on-the-second gold prices that are literally updated every second. Some examples of sites that do this are goldprice.org and gold.co.uk

Do's and Don'ts of Selling Gold

Here is some good advice to follow when selling gold:

  • DO stay sober - Some companies organise "gold parties", which mean making financial decisions while plied with drink which is not a good idea.
  • DO sell unloved trinkets and old gold fillings - Send broken chains, scratched rings, snapped brooches or dodgy bling from dumped exes. Old gold tooth crowns can fetch up to US $100, depending on their size and karat.
  • DO NOT send jewelry with gemstones - Remove diamonds and other stones before posting. The gemstone may be worth more than the gold and it is only the gold you will be paid for.

Comments

Submit a Comment

  • john000 profile image

    John R Wilsdon 

    3 years ago from Superior, Arizona

    this discussion about testing gold was very good. I particularly appreciate the reference to assay gold testing kit. Many prospectors would be happy to know how simple it is to get a testing kit. I know the use of acid requires safety measures, but so does prospecting! Thanks again for an informative hub.

  • annart profile image

    Ann Carr 

    5 years ago from SW England

    Very interesting. I generally prefer to wear silver but as I've got older I've worn more gold and the deep golden colour is beautiful. I love the 'slave bangles' where you have one bracelet white gold, one yellow and one red; they go together very well. In fact, I like mixing my silver and gold jewelry, even on one finger. Up, useful & interesting. Ann

working

This website uses cookies

As a user in the EEA, your approval is needed on a few things. To provide a better website experience, bellatory.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://bellatory.com/privacy-policy#gdpr

Show Details
Necessary
HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
LoginThis is necessary to sign in to the HubPages Service.
Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
AkismetThis is used to detect comment spam. (Privacy Policy)
HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
Features
Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
MavenThis supports the Maven widget and search functionality. (Privacy Policy)
Marketing
Google AdSenseThis is an ad network. (Privacy Policy)
Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
Index ExchangeThis is an ad network. (Privacy Policy)
SovrnThis is an ad network. (Privacy Policy)
Facebook AdsThis is an ad network. (Privacy Policy)
Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
AppNexusThis is an ad network. (Privacy Policy)
OpenxThis is an ad network. (Privacy Policy)
Rubicon ProjectThis is an ad network. (Privacy Policy)
TripleLiftThis is an ad network. (Privacy Policy)
Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
Statistics
Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)