Tests 18k gold using Auracle electronic tester. 18k yellow gold, onyx and seed pearl necklace in great antique, wearable condition. Found at an estate and being sold as found, has some surface dust and buyer is responsible for any cleaning or polishing. 16" chain, pendant measures 1" x 3/4". Clasp is marked as shown - maker is believed to be Helgen Mfg. Measures 8.0 grams non-magnetic