Pease & Curren lab evaluated three different gold testers and the results may surprise you.

What we evaluated:

  • an inexpensive 6-acid test kitfrom Star Struck LLC
  • a low-priced electronic tester, ET18 from R S Mizar
  • a high-priced electronic tester, GXL-24PRO by TRI Electronics.

We chose pieces of 10K, 14K, and 18K gold (both white and yellow), silver, and gold plated silver. Prior to testing, we used a table-mounted Innov-X Alpha XRF unit to verify the composition of each piece.  Each piece was tested first on the surface with no preparation, then with surface preparation as prescribed by the tester’s manufacturer.

Star Struck6-Acid Test Kit RS Mizar ET18   Electronic Tester TRI Electronics   GXL-24PRO Electronic Tester
10K accurate accurate accurate
10 K prepped accurate not accurate tested lower
14K accurate not accurate tested lower
14K prepped accurate not accurate tested lower
18K not consistent not accurate tested higher (19-23K)
18K prepped not consistent not accurate tested higher   (18-20K)
Silver accurate not accurate accurate
Silver prepped accurate not accurate accurate
Gold Plated   Silver surface accurate not tested surface tested lower
Gold Plated   Silver prepped accurate except on chain not tested inconsistent
Gold Filled surface accurate not tested surface inconsistent
Gold Filled   prepped indicates not karat not tested not accurate


Bottom line:  Hands down, the most consistent of the testers was the acid test kit.  Neither of the electronic testers was up to par, and the least accurate of the testers was the ET18.

What does this mean for our customers?

We recommend using caution when performing tests on unknown karat gold pieces as virtually all testers (including X-ray) can be fooled by surface layers that don’t reflect the composition of the base metal.  For the most accurate results, scratch the surface before testing, and use an acid test kit as recommended by the manufacturer.