{"product_id":"gold-test-stone-arkansas-novaculite-usa-3x1-5-8x1-4","title":"Premium Gold Test Stone-Made in the USA 3\" x 1-5\/8\" x 1\/4\"","description":"\u003cp\u003eA professional-grade gold testing stone made in the USA from natural Arkansas black novaculite, quarried and cut domestically. Used by jewelers and metalsmiths to test precious metals, this stone—also known as a streak stone or touchstone—provides a reliable surface for acid-based karat testing. Beware of cheap imitations made of glass, which stain and degrade quickly under repeated use.\u003c\/p\u003e\u003cp\u003eTo test a metal item, rub or scratch it across the stone's surface, then apply testing acid (sold separately) to the rubbing. An experienced user can determine the metal type based on the acid's reaction. For comparative karat testing, rub a known gold testing needle or verified gold sample alongside the test item's rubbing, apply acid to both, and compare the reactions—a similar reaction indicates similar karat content.\u003c\/p\u003e\u003ch3\u003eFeatures\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMade in the USA from natural Arkansas black novaculite\u003c\/li\u003e\n\u003cli\u003eQuarried and cut domestically for consistent quality\u003c\/li\u003e\n\u003cli\u003eSuitable for acid-based precious metal testing\u003c\/li\u003e\n\u003cli\u003eAlso known as a streak stone or touchstone\u003c\/li\u003e\n\u003cli\u003eSupports both reaction-based and comparative karat testing methods\u003c\/li\u003e\n\u003cli\u003eResists staining and degradation—unlike glass imitations\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eDimensions\u003c\/th\u003e\n\u003ctd\u003e3\" x 1-5\/8\" x 1\/4\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003eNatural Arkansas black novaculite\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOrigin\u003c\/th\u003e\n\u003ctd\u003eMade in the USA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003ch3\u003eNotes\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eTesting acid is sold separately and is required for acid-based testing.\u003c\/li\u003e\n\u003cli\u003eGold testing needles or verified gold samples are required for comparative karat testing.\u003c\/li\u003e\n\u003cli\u003eAccurate results depend on the experience of the user performing the test.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Otto Frei","offers":[{"title":"Default Title","offer_id":43581742121174,"sku":"156.712.5","price":45.65,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0609\/9832\/0342\/files\/premium-gold-test-stone-made-in-the-usa-3-x-1-58-x-14-otto-frei.jpg?v=1719957418","url":"https:\/\/www.ottofrei.com\/products\/gold-test-stone-arkansas-novaculite-usa-3x1-5-8x1-4","provider":"Otto Frei","version":"1.0","type":"link"}