{"id":7476,"date":"2021-10-02T14:34:54","date_gmt":"2021-10-02T12:34:54","guid":{"rendered":"https:\/\/ssef.ch\/?p=7476"},"modified":"2022-11-02T15:18:20","modified_gmt":"2022-11-02T14:18:20","slug":"update-on-unheated-mozambique-rubies","status":"publish","type":"post","link":"https:\/\/www.ssef.ch\/jp\/update-on-unheated-mozambique-rubies\/","title":{"rendered":"Update on unheated Mozambique rubies"},"content":{"rendered":"\n

by Dr. M.S. Krzemnicki, first published in Facette 26<\/a> (May 2020) <\/p>\n\n\n\n

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Figure 1: <\/strong>Iconic rubies from Mozambique all tested by SSEF and described below, all of exceptional size and quality. Photo assemblage: M.S. Krzemnicki, SSEF. <\/figcaption><\/figure>\n\n\n\n

In the past decade, rubies from Montepuez in the Cabo Delgado province of northeast Mozambique have been the most significant source of gem-quality rubies in the market. <\/p>\n\n\n\n

These include iconic stones\nsuch as the Rhino ruby (22.04 ct), the Scarlet\nDrop (15.95 ct), the the Heart of Mozambique (8.08 ct), and the Eyes of the Dragon (matching pair of 11.3 ct and 10.7 ct), to name only\na few (Figure 1). The best of this material\nis characterized by a very homogeneous\nand beautifully saturated red colour and an exceptional purity, very difficult\nto be matched by rubies\nfrom other sources.<\/p>\n\n\n\n

The presence of iron and traces of titanium in these rubies results in some cases in subtle slightly bluish zones, thus\nslightly shifting the colour of these\nrubies to purplish red, at least in part of their volume (Figure 2). This explains, in our opinion, why quite a substantial number\nof fine rubies\nfrom Mozambique have been treated\nby a so-called low-temperature heating (at about\n1000 \u00b0C) in recent years,\naiming to remove\nthis slight bluish hue.<\/p>\n\n\n\n

Originally a challenge for\nlabs, the detection of such low-temperature rubies has become more straightforward in recent months,\nbased also on research conducted at SSEF and detailed in SSEF press release published 12th September 2018 (see also Facette 2019, page 9).<\/p>\n\n\n\n

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Figure 2: <\/strong>Matching pair of unheated Mozambique rubies (7.69 ct and 7.16 ct) with excellent purity, both showing subtle bluish zones. Although evident in this photo (due to the white background), this effect is less pronounced when looking at these stones in reality with their apparent colour dominated by internal reflections. Photo: J. Xangsongkham, SSEF. <\/figcaption><\/figure>\n\n\n\n

As a positive side effect of research into this issue and the gearing-up of SSEF and other labs to safely detect such low-temperature heated
\nrubies, we have seen in the past few months a\ngrowing number of Mozambique rubies with very subtle blue hues in our\nlaboratory. This indicates that such stones\nare currently rather\nkept unheated, even with what was considered a few years ago a\nslight blemish in colour. This is done to maintain and safeguard the unheated status of the ruby and to acknowledge this slight colour shift in the stone as part of its individuality and beauty (Figure 2). \n\n\n\n<\/p>\n\n\n\n

Want to learn more about ruby origins and treatments? <\/strong><\/p>\n\n\n\n