[Jewelry making - Article 00189] - Re: [Orchid] When they started making synthetic Alexandrite

[The Doctor]

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>     Could you tell me what year they started making synthetic
>     Alexandrite I have a client who has a ring from the sixties and
>     asked me this question 

    The year was 1973, but that doesn't necessarily mean your client's
    stone is natural, or even alexandrite. Color-change corundum was
    developed around 1909, and has been purchased by unsuspecting people
    ever since, as alexandrite for birthstones. It is still widely
    offered as an affordable birthstone alternative to natural
    alexandrite. Check your supplier's catalog. If they practice full
    disclosure, you'll see what I mean...read the fine print. Most of us
    have Rio Grande's Gems and Findings catalog. Check their simulated
    (not synthetic) alexandrite listings. 

    Actual synthetic alexandrite has been maufactured by both the
    Czochralski and flux methods, and the most obvious difference is in
    the inclusions. Flux veils, gas bubbles, metallic platelets and
    curved striae will be evident in synthetic alexandrite, depending on
    the method of manufacture. Also, synthetic alexandrite often has a
    stronger reaction to UV light than natural does. Additionally, both
    synthetic types have modifying hues in their color changes that
    differ from each other, and from natural material. Natural
    alexandrite from different locations also vary in color. 

    Synthetic color change corundum can have similar inclusions to
    synthetic alexandrite owing to similar manufaturing processes.
    Refractive index and birefringence are also different. Specific
    gravity is another clue, but you'd have to remove the stone to check
    that. 

    To sum up, the year your client's ring was made is a very weak
    indication of whether it contains a natural alexandrite, but it is a
    start. Any experienced gemologist can tell, and most of us do IDs
    for reasonable prices, i.e., the cost of a decent lunch or dinner. If
    it is a natural stone, a written appraisal would be worth the extra
    money, too. 

James S. Duncan, G.G.
James in SoFL
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