{"product_id":"dr-hannemans-poor-mans-chelsea-filter-2000s","title":"Dr. Hanneman's \"Poor man's Chelsea Filter\" 2000s","description":"\u003cp class=\"p1\"\u003eThe \u003ci\u003e“Poor Man’s Chelsea Filter”\u003c\/i\u003e is part of a family of coloured gemological filters produced by Dr. W. William (“Bill”) Hanneman. He developed a range of inexpensive colour filters designed to help hobbyists, students, and amateur gemologists perform simple visual tests on gemstones without needing expensive instruments. These filters were intended to mimic or expand on the principles of the \u003ci\u003eChelsea filter\u003c\/i\u003e (originally invented in 1934 by Anderson \u0026amp; Payne) but with a broader and more accessible design and price point. \u003c\/p\u003e\n\u003cp class=\"p1\"\u003eIn listings of \u003ci\u003eHanneman filter sets\u003c\/i\u003e — such as those marketed under names like “The Works,” “Bead Buyer’s \u0026amp; Parcel Picker’s Filter Sets,” or the PMCF itself — the Poor Man’s Chelsea Filter is specifically included as one element in this line of affordable gem filters. \u003c\/p\u003e\n\u003cp class=\"p1\"\u003eAccording to product descriptions, the PMCF was developed to operate on similar optical principles to a Chelsea filter, though with \u003ci\u003edifferent transmission bands\u003c\/i\u003e that allow broader wavelengths (for example, a transmission centre around 525 nm rather than the strict yellow-green\/deep red bands of the classic Chelsea filter). This makes its reactions somewhat comparable but \u003ci\u003enot identical\u003c\/i\u003e to those of a true Chelsea filter. \u003c\/p\u003e\n\u003cp\u003e\u003cspan class=\"s1\"\u003e\u003c\/span\u003eThe inclusion of the filter in modern filter sets (e.g., models listed from the 2000s like “PMCF Set – Model 2005” in The Works filter set) strongly suggests that by the early 2000s the PMCF was already in production and being marketed as part of Hanneman’s affordable gem filter line. \u003c\/p\u003e\n\u003cp class=\"p1\"\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":51547918041408,"sku":null,"price":0.0,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0963\/0397\/2672\/files\/PMCF_1.gif?v=1771491336","url":"https:\/\/gems.studio\/products\/dr-hannemans-poor-mans-chelsea-filter-2000s","provider":"Gems.studio","version":"1.0","type":"link"}