Coin collectors and bullion investors in Connecticut Shoreline often ask us what equipment we use to test their coins — and why it matters. The answer is the Sigma Metalytics Precious Metal Verifier, a professional instrument that has changed how serious precious metals buyers operate. Here's everything you need to know about how it works and why it gives both buyers and sellers confidence that the readings are accurate.
What Is the Sigma Metalytics?
The Sigma Metalytics is an electromagnetic precious metal verifier that measures the electrical conductivity (sigma) of metal. Different metals and alloys have distinctive conductivity signatures — gold, silver, platinum, palladium, tungsten, copper, and their alloys each produce different readings at different frequencies. The device maps these readings against known standards and returns an instant purity reading.
How It Differs from Other Testing Methods
- Acid testing: surface-only, destructive to the tested area, cannot detect tungsten cores
- Specific gravity / density testing: detects tungsten fakes, but requires submersion in water and can't identify alloy composition
- XRF (X-ray fluorescence): highly accurate but expensive ($20,000+), measures only the surface layer
- Sigma Metalytics: tests full depth non-destructively, detects tungsten, identifies alloy composition, costs a fraction of XRF
The Sigma Metalytics reads through the entire thickness of a coin or bar — not just the surface. This is critical for detecting gold-plated tungsten counterfeits, which have fooled simpler methods for years.
What Coins We Test with the Sigma
- American Gold Eagles (22K / .9167 fine) — the most common US gold coin we see
- American Gold Buffalos (24K / .9999 fine) — pure gold, reads perfectly on the Sigma
- Canadian Gold Maple Leafs (.9999 fine) — extremely common in Connecticut estate collections
- South African Krugerrands (22K) — very popular in the 1970s–80s, frequently appear in estates
- American Silver Eagles (1 oz .999 fine) — the benchmark for silver coin testing
- Morgan and Peace Dollars (90% silver) — common in coin collections, Sigma confirms 90% silver instantly
- Pre-1965 US dimes, quarters, and halves (90% silver) — junk silver bags tested in bulk
- Generic silver rounds and bars — critical to distinguish .999 silver from silver-plated copper
Detecting Counterfeit Coins
The counterfeit coin market has grown significantly as precious metal prices have risen. Modern fakes include gold-plated tungsten coins that match the correct weight and dimensions of genuine gold Eagles and Maple Leafs. The Sigma identifies these immediately — tungsten reads completely differently from gold at the instrument's test frequencies, regardless of the coin's outer plating or surface finish.
What a Sigma Reading Looks Like
The device displays a bar chart across multiple frequency channels. A genuine American Gold Eagle produces a signature pattern centered in the 22K range. A genuine Silver Eagle produces a pattern centered in the .999 silver range. Counterfeits, silver-plated items, or base metal pieces produce patterns that fall outside these windows — and the device flags them immediately. We show you this screen during every test.
How This Protects You as a Seller
If you've inherited a coin collection and aren't certain what's genuine, the Sigma gives you objective confirmation before any transaction. We've helped sellers discover that what they thought were gold coins were actually gold-plated commemoratives worth only a few dollars — and also confirmed that pieces sellers doubted turned out to be genuine gold. The scanner protects honest sellers from being shortchanged and protects buyers from purchasing counterfeits.
Bring your gold or silver coins to Gold Buyers Connecticut for a free Sigma Metalytics test. We'll tell you exactly what you have and what it's worth at today's spot price — no obligation.