My final and last contribution to Garnet Week with Blue Color Change Garnet and following later with the rarest Garnet known to man (Sorry for the longer note/info below, but so much info on this very rare Blue Color Change Garnet)... :D Simply put and obviously learned this week by many members here (my intentions to teach this), that when thinking of Garnet, most people think of red gemstones. Garnet most commonly occurs in red, and the origin of the name Garnet lies in this deep red hue. The name Garnet comes from the Medieval Latin word, Granatum, which is an adjective meaning dark-red. Color Change Garnet is one of the most rare, interesting, and phenomenal of all gems and the only example of Blue Garnet. In the past, gemological literature referred to Garnet as occurring in every color but blue, but this is clearly not the case anymore and some Madagascar and Tanzanian color change Garnets are indeed blue under the right light conditions. The color change can be intense and equal to the color change of top quality Alexandrite indeed. The color change phenomena is caused by a relatively high presence of vanadium or chromium in the crystal matrix and Color Change Garnets can easily be mistaken for Alexandrite. Some of the best stones are from the deposit in Bekily, Southern Madagascar but top stones were also found in Nandagala, Southern Tanzania and in Chavia, on the border between Tanzania and Kenya. Color change ability is an extremely rare occurrence that is known to occur in only a handful of gems. The color change ability is present in rare specimens that have formed with two light transmission windows (rather than one) that are approximately the same size. For example, a red gemstone will appear red because it absorbs all frequencies of light except for red; but a gemstone that absorbs all frequencies of light except for blue and red, will appear blue when the light source is rich in blue wavelengths, and will appear red when the light source is rich in red wavelengths. Fluorescent light is rich in blue, whereas incandescent light and candlelight are rich in red wavelengths. Natural daylight has a very well-balanced spectrum throughout most of the visible light wavelengths. Thus why I teach newer rockhounds that using a full spectrum sunlight is the best light for photographing rocks, gems, and minerals. To appreciate the full range of color change in these stones, one needs to observe the stones under early morning light, fluorescent lighting, late afternoon sunlight, and incandescent light. Cool daylight above 6200K will highlight the blue or green colors while warm daylight around 3500K will make the stones appear red. Early morning light will make the stones look greenish or bluish while afternoon light will make them appear red. The best stones display a color change from greenish or bluish in daylight to red or purple under incandescent light. NFS by no means...Thanks! :D
Posted on: Sat, 11 Oct 2014 22:57:12 +0000
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