Australian Facetors' Guild Limited

Dark stones

  • 30 May 2024 11:12 PM
    Message # 13363512


    please advise me what diagrams to use for dark stones. Possibly a link to information.

    Thank you


  • 31 May 2024 5:56 PM
    Reply # 13363967 on 13363512

    Hi Zoltan,

    it depends on how dark the stone is.  I have some Kerala Garnets that are so saturated they look black when cut even though you can see light through them,  cut as a brilliant they are black.  I’m going to try 4 large reflector facets on the pavillion cut at 2degrees above the critical angle and a shallow crown that is mostly table.  This is to minimise the distance light has to travel through the stone.  If that doesn’t work, the only cut for them is a rose cut with no pavillion, it won’t matter.

    but ordinary saturated garnets benefit from a low crown and pavillion with large reflector facets.

    if you can get it from the net, Jeff Graham’s Lighthouse Cut was designed for dark garnet.

    if you are cutting closed C tourmaline, chose a tourmaline cut to minimise reflection along the C axis which will darken the stone



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