Two trusted methods, one essential practice. Explore which gold testing approach works best for your shop.
A jeweler’s biggest challenge and a customer’s biggest concern? Uncertainty. Whether you’re dealing with an unknown repair job, sorting scrap, or preparing an item for resale, not knowing exactly what you’re working with can slow you down and risk your reputation. Gold testing might seem like just another step in your workflow, but what if it could be another key tool that helps you protect your business and build trust with your customers? Just those few extra minutes can make it the simple step that potentially saves you major time — and profit — in the long run.
While the basics haven’t changed, the tools have. Today’s jewelers have two trusted methods at their fingertips: traditional acid testing and fast digital testing. Here’s our guide to seeing how each method fits different workflows and needs along with tips to get the most accurate results and support.
Which Gold Testing Method Should You Choose?
First, it’s important to understand why gold testing can be an essential practice for your shop. Similar to diamond or gemstone testing, gold testing in any capacity can protect your reputation and supports several areas of your business. Whether you're confirming the karat of an item for resale, assessing materials before a repair, or evaluating scrap, gold testing helps you move forward with confidence and gives your customers added peace of mind.
As for the method you choose, your decision will depend on your shop’s volume, how often you plan to test, and the level of assurance you need based on incoming jobs. A general rule of thumb: acid testing may be your best choice for working at the bench, while digital testing offers convenience. No single method is better than the other; however, any jeweler can benefit from using both acid testing and digital testing. It’s all about what works for you.
What Is Acid Testing?
Acid testing — one of the oldest and most traditional ways to check gold content — is based on a reaction from solutions placed on a testing stone. While it is more time-consuming than its counterpart, it’s accessible for lower-cost operations and works well for those who prefer to test at the bench.
How to Test With Acid
First, you’ll start by slightly filing into the metal to get past any plating, if necessary. Then, make a small mark on a testing stone. From there, apply a drop of acid specific to the karat level you want to test, such as 10K, 14K, 18K, or 22K. The reaction is what should tell you the estimated gold content of your piece — if the mark fades or disappears, it’s likely lower than that karat; if it stays, the metal meets or exceeds it.
When to Use This Method
Acid testing is a good fit when
What You’ll Need
Here’s what you’ll want to have on hand to run a proper acid test, plus a few safety basics to make the process smooth and secure.
- Gold test stone
- Acid testing kit with karat-specific solutions
- Filing tool or abrasive tools to get past plating
- 400-grit sandpaper for post-test cleanup
- Gloves, tweezers, and safety goggles
Tip: Always test in a well-ventilated area and store acids securely when not in use.
What Is Digital Testing?
Digital testing uses electronic conductivity to estimate the gold content of a piece without needing to leave a mark. With a wider range of equipment options to choose from, this method suits different budgets and experience levels. While it may seem like a larger investment upfront, it’s a practical option for shops that test regularly, need a secondary testing method, or want a cleaner approach overall.
Using Digital Gold Testers
Depending on your equipment, start by turning on and calibrating your tester. Then, touch the probe to a clean, flat part of the piece you’re testing. Within seconds, the tester should display an estimated karat or purity reading based on how the metal conducts electricity. Every digital tester is different, so it’s important to follow the directions of each manufacturer to ensure proper results.
When to Use This Method
Digital testing is a great fit for jewelers or shops that ar
- Testing gold-filled and plated pieces, and standard gold alloys.
- Needing fast, no-mess results.
- Testing with customers and looking for a cleaner approach.
Tip: Make sure the testing area is free of dust, oils, or residue to help your device read as accurately as possible. The pens contain a solution that will dry out over time; these are consumables, so make sure you calibrate regularly to ensure consistency across tests.
Next-Level Accuracy With GemOro®
The GemOro® Superior Instruments XRF Gold & Precious Metal Analyzer takes digital testing a step further. Using X-ray fluorescence, this advanced device reads up to 20 microns deep, often eliminating the need to file on both standard and plated pieces. It delivers a full breakdown of metal composition, including percentage values of each alloy, so you can verify karat and detect under-karated metals with certainty. With a quick data transfer, this device also connects via Wi-Fi, Bluetooth, or USB and easily exports test results for your records.
Tips and Tricks
A few small steps can make a big difference in how accurate and consistent your test results are. Here are some helpful reminders:
When in doubt, start with a magnet. This quick tool helps rule out non-precious or heavily plated metals before you spend time testing.
File beneath the surface. Make sure you’re getting past any plating so your results reflect the actual metal.
Take care of your tools. Check acid solutions often and replace as needed. For digital testers, clean the probe, store the unit in a dry place, and recalibrate regularly.
Know your tolerances. Acid testing gives a general estimate and takes a bit of interpretation. Digital testers are more precise but can vary depending on the alloy. Knowing the strengths of each method helps you test with confidence.
A Smarter Way to Handle Scrap
Need another solution? When you’re working with mixed materials or testing isn’t practical, Stuller’s Precious Metal Clean Scrap Program offers a straightforward solution for turning precious metals into value you can use.
Send us your clean gold, silver, platinum, or palladium scrap. Once we receive it, our experts will verify and evaluate the materials, then provide you with a payout offer. You can choose to receive a check or direct deposit when you select Stuller account credit, which can be used toward future purchases of metal grain, bars, coins, or rounds. It’s a trusted way to handle scrap with less hassle and more confidence.
Keeping Your Reputation Safe
Whether you’re working at the bench or face-to-face with a customer, having the right testing method on hand gives you the confidence to move forward with the job. While our guide covers the benefits and setbacks of each, remember that your shop can always benefit from more than one testing approach. Again, it’s not about choosing the best method — it’s about finding what works best for you.
As always, you can rely on Stuller to support every step of your workflow — from providing trusted testing supplies and equipment to offering refining services when you need a second opinion. For any additional questions regarding metals and materials, reach out to our Tools Tech Team using ext. 4300 to speak with our in-house specialists.