How to Calculate the Value of Impure Gold

Use a magnifying glass to read the karat number on each piece of gold. The first step is to determine whether your gold is genuine. Classifying gold by karat not only helps you assess its value but also identifies items that are not real gold.

• If the karat number is not visible, you can hire a reputable gold dealer to inspect it. Some of your gold items might only be gold-plated, and a gold dealer can confirm this through a chemical test.
• Note that most gold jewelry produced before 1980 is slightly lower in quality than the marked karat value. For example, jewelry marked as 18K might actually be 17-17.5K. In 1980, laws regarding gold jewelry markings and purity standards were revised.

Conduct an acid test on any item you suspect. If you're unsure whether an item is gold after examining it with a magnifying glass, proceed with testing. You have two options: the acid test and the Skey test. The acid test requires a gold testing kit or individual components (acid and a testing stone).

• These tools can be purchased online or from jewelry stores at a low cost, either as individual items or as a kit. A typical kit includes bottles of 10K, 14K, 18K, and 22K gold testing acid, usually nitric acid, along with a testing stone made from materials like novaculite or other types of flint. Some kits may also include a scale.
• For jewelry claimed to be 14K gold, rub it on the stone and apply a drop of 14K acid to the mark. If the item is genuine 14K gold, the mark will remain unchanged. If it's 10K gold, the mark will turn brown. If the mark disappears entirely, the item is not gold.
• If the gold is unmarked, start with the lowest acid concentration and work up to 22K. The mark turning brown indicates the gold is of the next lower karat. For example, if 18K acid causes no change but 22K acid turns the mark brown, the gold is considered 18K. Similarly, if 14K acid causes no change but 18K acid turns the mark brown, the gold is 14K, and so on.

Use the Skey test. For the Skey test, you first need to purchase a gold testing pen designed for this method. These pens cost around 1 million VND and can perform up to 1000 tests. This test is a safer alternative to acid testing and is highly accurate for metals like platinum.

• On the suspected gold jewelry, slowly draw a line about 5mm long, going over it four times without lifting the pen from the metal.
• Immediately after, draw a line on any white paper.
  • If the gold is below 10K, the line will be light brown and turn green within seconds.
  • For 10K gold, the line will be light brown.
  • For 14K gold, the line will be dark brown.
  • For 18K gold, the line will be orange.
  • For 22K gold, the line will be yellow.
  • For 24K gold, the line will be red.
  • If no line appears, the item is not gold.

Separate gold coins from the rest of your gold. If you have gold coins, they may hold collectible value beyond their metal content. This value depends on their age, rarity, and overall condition. In such cases, it's best to have them appraised by a coin dealer. This step is crucial as it could significantly increase their worth.

• If you have experience with online auctions, you can sell the coins online, but you'll need a certificate of authenticity to convince buyers to bid higher. Additionally, using a secure payment system will reassure buyers. The benefit of auctioning (provided you know the coin's true value) is that the final price may far exceed your asking price if multiple collectors participate.
• Read 'How to Determine the Value of Gold Coins' for more information on evaluating coins.

Purchase a scale to weigh your impure gold. Determining the weight of your impure gold will help you calculate its base value. This isn't necessarily the price you'll receive but serves as a reference point when negotiating.

• Buy a jeweler's scale. These are available online for less than 1 million VND. They provide the most accurate measurements, as they are designed specifically for weighing precious metals.
• Use a kitchen scale if you can't purchase a jeweler's scale. If you already own one, it can suffice for weighing gold. However, most inexpensive kitchen scales have a minimum weight limit of 10g, so evaluate their functionality before using them for gold.
• If you can't or don't want to buy a scale, take your gold to a jeweler to have it weighed.

Weigh the impure gold. Remember to weigh the gold in groups based on their karat quality. Place the gold on the scale and allow it to stabilize before taking the reading. Depending on the type of scale, there may be a needle pointing to a specific gram value, and you can take the measurement from that point. However, more expensive scales will have a digital display, allowing you to read the measurement directly from the screen.

Convert to grams if the scale measures weight in ounces. The conversion rate is 28.3495231 grams per ounce, or approximately 14.175 grams per half-ounce.

• Typically, you won't have 30 grams of gold for each karat value, and if you do, you should group it by karat quality. Keeping all calculations in the same weight unit will make the process more convenient later on.

Determine the current value of the gold. Knowing how much your gold is worth is crucial when you start the selling process. There is a formula to calculate the exact value of impure gold in grams, and the only variable in this equation is the current market price of gold. You can find the current market price online or check local newspapers. Gold is priced per troy ounce, with one troy ounce equaling 31.1 grams. The price of gold fluctuates hourly based on supply and demand, so the afternoon price may differ significantly from the morning price.

• It's best to get real-time updates from the internet, which you can do while standing at the gold buyer's counter by accessing the internet on your mobile phone.

Divide today's gold price per ounce by 31.1 to get today's gold price per gram. For example, if today's gold price per ounce is 36.32 million VND, then today's gold price per gram is 1.17 million VND (36.32 million VND / 31.1).

Multiply by the gold's purity. For each group of gold, divide the karat by 24 and then multiply the result by today's gold price per gram. For example, if you have 10K gold and the current gold price is 36.32 million VND per ounce, or 1.17 million VND per gram (36.32 / 31.1), then the value of impure gold is 1.17 million VND x 0.4167 = 487,000 VND per gram. Use the following conversions to price your gold.

• 10K = 10/24 = 0.4167
• 14K = 14/24 = 0.5833
• 18K = 18/24 = 0.750
• 22K = 22/24 = 0.9167

Conduct an assay to confirm the gold's value. Gold must still be assayed to determine the actual percentage of gold. For example, 14K gold when assayed will yield 0.575%. When melted, the weight of the gold will decrease due to the alloys used in its creation.

• During the assay, a sample of gold is taken from your collection, processed, and evaluated for purity. The sample is melted, separated, and weighed to determine its purity.

Multiply the gold price per gram by the weight in grams. If you have 10 grams of 10K gold and the gold price is calculated at 487,000 VND per gram, then the value of your gold is 10 x 487,000 VND = 4.87 million VND. Some examples:

• If you have 5 grams of 14K impure gold and today's gold price is 36.32 million VND, divide 36.32 million by 31.1 to get 1.17 million VND. Multiply that by 0.5833 (14K) to get 682,000 VND per gram. Multiply 682,000 VND by 5 grams to get 3.41 million VND.
• If you have 15.3 grams of impure gold, divide 36.32 million VND by 31.1 to get 1.17 million VND, then multiply by 0.4167 (10K) to get 487,000 VND per gram. Multiply 487,000 VND by 15.3 grams to get 7.45 million VND.
• Most people use grams for these calculations, but some gold buyers use pennyweights instead. One troy ounce equals 20 pennyweights. You can substitute 20 for 31.1 in the formula above to calculate in pennyweights. You can also multiply the weight in pennyweights by 1.555 to get the weight in grams, or divide the weight in grams by 1.555 to get the weight in pennyweights.