[Jewelry making - Article 00298] - Re: [Orchid] Using the term semi precious gems

[leonid surpin]

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Helen,

>     Yes the term is a little gory and nonedescript as the blood of a
>     pigeon isn't something most of us have seen, but I used the term as
>     I knew everyone on this forum would understand that I was talking
>     about decent quality rubies of a "highly prized" colour. 

    sorry for picking on your post, but it encapsulates so much
    misinformation that correction is in order. 

    The term "pigeon blood" used in the context it was intended,
    describes ruby so rare that none of us would probably ever come
    across. It is been used by dishonest gem dealers to sell their wares
    and regretfully they have been getting away with that for years. If
    someone offers you a "pigeon blood" ruby, my advice do not walk away
    from the deal, run from it. 

    "Pigeon blood" describes ruby which fluoresces under sun light.
    Fluorescence cannot be seen, but its presence manifested by
    noticeable inner glow of the gem. The colour appears to come from
    inside. The effect is partially due to the presence of extremely fine
    silk, which caused dispersion of colour throughout the gem. 

    The only way it could happen, the ruby must form in the iron free
    environment, and sufficient chromium must be present. Exsolution of
    titanium oxide must be complete and had been accomplished at a rate
    congenial to fine silk formation. Any variation from that scheme and
    very nice ruby would form, but not a "pigeon blood". 

    What it all mean is that true "pigeon blood" can be created in a
    lab, but probably never existed in nature, but some specimens can 
come
    real close. Where to draw the line which demarcates when "pigeon
    blood" becomes just a nice ruby is a very old argument and probably
    will never be resolved. 

    GIA recommends not to use the term at all. My view is that the term
    is too important to simply let go. Understanding of its true meaning
    it a better option. 

Leonid Surpin
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