{"product_id":"okuda-diamond-grading-microscope-c-1978","title":"Okuda Diamond Grading Microscope, c. 1978","description":"\u003cdiv\u003eDeveloped by Japanese gemologist and inventor Kazumi Okuda, this specialized diamond-grading microscope represents an important early attempt to make diamond grading more objective and reproducible. The instrument is documented by an Okuda Diamond Grading Microscope Reference Manual dated 1978, making circa 1978 the most appropriate date for this artifact. By January 1980, the microscope had been formally described in the Journal of Gemmology as a new commercial instrument from Okuda Jewelry Technical Institute Co. Ltd., Tokyo.\u003c\/div\u003e\n\u003cdiv\u003e\u003c\/div\u003e\n\u003cdiv\u003eOkuda was a particularly innovative figure in Japanese gemology during the late 1970s and early 1980s. His work extended beyond microscopy: he developed techniques for evaluating diamond cut and light return using colored reflectors, pioneered microscopic identification\/inscription of diamonds, and held patents relating to diamond marking. His optical approach subsequently influenced the development of the FireScope and, indirectly, later Hearts-and-Arrows and Ideal-Scope methods of diamond-performance evaluation. \u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eThe microscope was designed to bring color, clarity and cut\/proportion assessment into a single controlled viewing system. For color grading, the original instrument employed a 10× wide-field eyepiece giving approximately 20× overall magnification, together with a yellow wedge filter whose transmission peaked at approximately 585 nm. The wedge represented a controlled range corresponding approximately to the GIA E–J color grades, allowing the grader to compare the diamond visually against a standardized reference rather than relying entirely on memory or expensive master stones. Its eyepiece also incorporated a clarity-grading graticule, with numbered circles used to estimate the apparent area of inclusions; the resulting measurements could be converted to a CIBJO or national clarity grade. The precision XY stage allowed inclusion locations to be recorded, while the spring-loaded holder could accommodate mounted stones. A separate green-filtered illumination system was provided for viewing the microscopic code that Okuda's system could place on a diamond's table. Most significantly, the instrument belongs to the early generation of optical devices that attempted to assess diamond cut quality and light return, an idea that would become highly influential in the development of modern optical-performance and Hearts-and-Arrows evaluation.\u003c\/div\u003e","brand":"Gems.studio","offers":[{"title":"Default Title","offer_id":67714905506112,"sku":null,"price":0.0,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0963\/0397\/2672\/files\/Okuda01.avif?v=1791291125","url":"https:\/\/gems.studio\/products\/okuda-diamond-grading-microscope-c-1978","provider":"Gems.studio","version":"1.0","type":"link"}