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Gemstones, Minerals & Fossils
Gemstones and Minerals
Lets Talk Cuts
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<blockquote data-quote="Lefty" data-source="post: 467315" data-attributes="member: 2976"><p>Yes indeed :Y: </p><p></p><p>On the subject of windows, a properly-cut stone can still display a "tilt window" - that is, it will show a window when the stone is tilted far enough away from the normal face-up viewing angle as the tilt away from normal breaches the stones critical angle from the perspective of the viewer. Of course, a stone is intended to be viewed straight down on the crown mostly so this isn't considered a problem <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite8" alt=":D" title="Big Grin :D" loading="lazy" data-shortname=":D" /> It's more noticable in lower RI stones like feldspar and quartz since their higher critical angle (41.5 degrees and 40.5 degrees respectively off the top of my head anyway) typically gives less room between the culet angle and critical. It tends to be less noticable with really high RI stones like zircons, with a critical angle of around 30.5 degrees.</p></blockquote><p></p>
[QUOTE="Lefty, post: 467315, member: 2976"] Yes indeed :Y: On the subject of windows, a properly-cut stone can still display a "tilt window" - that is, it will show a window when the stone is tilted far enough away from the normal face-up viewing angle as the tilt away from normal breaches the stones critical angle from the perspective of the viewer. Of course, a stone is intended to be viewed straight down on the crown mostly so this isn't considered a problem :D It's more noticable in lower RI stones like feldspar and quartz since their higher critical angle (41.5 degrees and 40.5 degrees respectively off the top of my head anyway) typically gives less room between the culet angle and critical. It tends to be less noticable with really high RI stones like zircons, with a critical angle of around 30.5 degrees. [/QUOTE]
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Gemstones, Minerals & Fossils
Gemstones and Minerals
Lets Talk Cuts
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