{"product_id":"gagb-chelsea-colour-filter-post-2001","title":"GAGB Chelsea Colour Filter Post-2001","description":"\u003cp data-start=\"0\" data-end=\"690\"\u003eThis Chelsea Colour Filter, branded \u003cstrong data-start=\"36\" data-end=\"89\"\u003e\u003cspan class=\"hover:entity-accent entity-underline inline cursor-pointer align-baseline\"\u003e\u003cspan class=\"whitespace-normal\"\u003eGem-A\u003c\/span\u003e\u003c\/span\u003e Instruments\u003c\/strong\u003e, represents a post-2001 production example manufactured after the Gemmological Association of Great Britain formally adopted “Gem-A” as its public identity. In the early 2000s, the Association streamlined its institutional name—short for \u003cem data-start=\"328\" data-end=\"402\"\u003eThe Gemmological Association and Gem Testing Laboratory of Great Britain\u003c\/em\u003e—to strengthen global recognition and modernize its presence in print and online communications. The use of the Gem-A name and crest on this instrument situates it within this contemporary phase of the Association’s history, although the exact year of manufacture has not been documented.\u003c\/p\u003e\n\u003cp data-start=\"692\" data-end=\"1263\"\u003eFunctionally, the filter follows the established optical principle of the \u003cstrong data-start=\"766\" data-end=\"791\"\u003eChelsea Colour Filter\u003c\/strong\u003e, transmitting deep red and yellow-green wavelengths while suppressing much of the blue-green portion of the spectrum. Under incandescent illumination, chromium-bearing emeralds typically display a red or pink reaction, while many green simulants remain green. As with earlier examples, the instrument serves as a rapid screening aid and is intended for use alongside refractometry, spectroscopy, and microscopic examination rather than as a stand-alone diagnostic device.\u003c\/p\u003e\n\u003cp data-start=\"1265\" data-end=\"1793\" data-is-last-node=\"\" data-is-only-node=\"\"\u003eThe housing reflects modernized production methods compared with mid-twentieth-century metal-cased examples. Fabricated in molded white synthetic material and secured with metal screws, the design emphasizes durability, portability, and institutional branding. This post-2001 Gem-A example illustrates the continuity of traditional gemmological teaching tools into the twenty-first century, demonstrating how a diagnostic method developed in 1934 remains incorporated within contemporary gem education and professional practice.\u003c\/p\u003e\n\u003cp data-start=\"1265\" data-end=\"1793\" data-is-last-node=\"\" data-is-only-node=\"\"\u003e\u003cmeta charset=\"utf-8\"\u003e\u003cspan\u003eThis is a museum archives and no unit is available for sale at this moment. \u003c\/span\u003e\u003c\/p\u003e","brand":"Gems.studio","offers":[{"title":"Default Title","offer_id":51555144106304,"sku":null,"price":0.0,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0963\/0397\/2672\/files\/GAGB2001_2.gif?v=1771803178","url":"https:\/\/gems.studio\/products\/gagb-chelsea-colour-filter-post-2001","provider":"Gems.studio","version":"1.0","type":"link"}