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Blue Green Sapphire

This topic contains 3 replies, has 4 voices, and was last updated by Profile photo of zahaetc zahaetc 1 year, 1 month ago.

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  • #198884
    Profile photo of areias
    areias
    Participant

    I am hoping someone will shed some light on a question I have concerning Thermal Impact damage on Blue-green Sapphire.

    I am currently trying to find out if its possible to tell if a Sapphire has been damaged due Thermal Impact or other means?

    The stone in question has a Cleve across the stone that apparently is only visible at a certain angle in the correct lighting conditions.

    If an expert in the field of gemology has a look at a sapphire with this affliction, is there a 50 50 chance they can tell what the damage to the stone has been caused by?

    #198997
    Profile photo of sydp
    sydp
    Participant

    Hi I am not an expert but the sapphires I have dealt with are all volcanic.
    I have had plenty of experience in digging Central Qld (Australia) sapphires and cutting them. These are volcanic and most are broken and very rarely do you get a full crystal. This is because after the volcanic eruptions and the sapphires were sitting in about 15 metres of basalt over 50,000 million years of weathering being covered by sea at least 7 times and being washed and battered around most were broken and indeed have flaws/cracks in the stones. These are sometimes very hard to detect and you may only discover the flaw during the faceting of the gemstone

    as far as Thermal goes, I would suspect that in a lot of cases the fractures would be a healed fracture. meaning that it may have been fractured under extreme pressure but then healed again through the thermal process

    hope this helps

    #199109
    Profile photo of mhutton
    mhutton
    Participant

    An interesting thread. I don’t recall ever seeing a cleavage in a sapphire. Cleavage stated in the books for sapphire is, “None”. I agree with Syd above … more likely a fracture that has fingerprint healed. You do see discoid or halo fractures from heat treatment though. The only other thing that comes to my mind, without seeing the stone of course, would be the possibility of a twinning plane. Would you care to post a photo so we can see what you are seeing?

    #199193
    Profile photo of zahaetc
    zahaetc
    Participant

    Areias described it is only visible on certain lightening conditions and directions, its more likely a twinning plane

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