[Jewelry making - Article 00257] - Re: [Orchid] Diamonds unanswered

[The Doctor]

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>         Do you think that if all the money that has been spent on
>     diamond exploration were spent on say alexandrite exploration there
>     would be many more alexandrites on the market?  Would small
>     alexandrites be as common as small diamonds? How about any other
>     gemstone that we now consider rare? 

    If the same amount of money spent on mining diamonds were spent on
    practically any gemstone, I suppose there would be many more of
    them. But since diamonds are so widely marketed and alexandrite is
    not, it wouldn't be economically feasible to spend that kind of
    money on alexandrite mining. I don't believe that the conditions for
    the formation of alexandrite was ever as favorable as it was for
    diamonds, so I doubt that they would be as common. Diamonds have
    been found in every part of the world except Antarctica, whereas
    alexandrite has not. As far as other gemstones we consider to be
    rare concerning this discussion, I don't think so, either.
    Alexandrites, demantoid Garnet, Paraiba tourmaline - these and many
    other rare gemstones lack something diamonds offer: durability. I'll
    agree that there are tougher stones than diamond, but none of them
    can wear longer. 

>         Has anyone ever seen the actual pile of rough or cut diamonds
>     supposedly stored by DeBeers? 

    I haven't personally seen it, but all diamond rough is well
    documented. It's just too big a business to fudge about it. Most of
    De Beers' mining processes are mechanized, so it would be difficult
    for them to pretend otherwise. 

>         At what point in diamond size and quality does a stone qualify
>     as rare? 

    To me, any 'extra fine' gemstone qualifies as rare. The geologic
    conditions under which gemstones form are incredibly uncommon. There
    may be billions of carats of diamonds in the earth's mantle, but
    until there is a kimberlite (or lamproite) eruption to bring them to
    the surface, there they will stay. 

    Kimberlites are actually fairly widespread. In the 1990s, there were
    around 6,000 of them known around the world. The thing is, fewer
    than 1,000 of them contained any diamonds. If there are no diamonds
    in the kimberlite's path to the surface, there are no diamonds in
    the pipe. Of the 1,000 that contained diamonds, only perhaps 50 of
    them were diamondiferous enough to be economically mined, and only
    20 or so remain today. Now, here's what actually qualifies just
    about any diamond (indeed, any gemstone) as rare - The first
    diamond-bearing kimberlite eruption occurred around 2.5 billion
    years ago by scientific estimate. The newest emplacement happened
    around 20 million years ago. No one has ever seen one. There may be
    undiscovered, diamond-laden pipes still to be discovered, but in the
    end, supplies are limited. It is absolutely within the realm of
    possibility that we may eventually mine every diamond on the planet
    before any more reach the crust of the earth through a kimberlite
    eruption. And there's no guarantee that the next eruption will
    contain diamonds. In fact, the statistics are against it, 120:1. 

    While looking around the average diamond district, they don't seem
    rare - they seem to be everywhere. But the reality is that most are
    included, colored or in some other way (cut, etc) common (meaning
    less rare). The better the clarity and color, the larger the size,
    the more rare. And even supplies of inferior goods won't last
    forever. It may be another 20 million years (or longer) before any
    more diamonds are rushed to the surface. Personally, I'm not so sure
    the human race will be around that long. 

>          Does anyone know what percentage of diamonds that are mined
>     are cuttable into jewelry grade diamonds? 

    It depends on the mine, itself. Primary deposits such as kimberlite
    pipes have the lowest percentage of cuttable material. Or, at least
    makable material. Other sources, such as alluvial and marine
    deposits have a typically lower overall yield in carat weight, but
    the rough has been tumbled to the point that either the finest
    pieces with the fewest flaws remain intact, or they make it to the
    deposit already broken or cleaved into smaller pieces. In that case,
    the work of planning, cleaving and sawing is minimalized to the
    point that a much larger percentage of the rough is cuttable. In
    1960, more than 80 percent (by weight) of diamonds were recovered
    from alluvial deposits. By the early 1990s, it accounted for only 25
    percent, so percentages fluctuate over the years. In marine mining
    in particular, gem quality stones are extremely high by percentage.
    For example, in Namibia, any fractured stones that survived the trip
    were broken apart during the trip. As a result, around 90 to 95
    percent of the diamonds mined there are gem quality. 

    According to one GIA publication, the world's estimated diamond
    production in 1999 breaks down like so: 

    15 percent gem-quality rough
    39 percent near-gem rough
    46 percent industrial rough.

    The actual amount of finished goods is somewhat hazy from there. As
    technology increases, more and more near-gem and industrial rough
    can be acceptably enhanced or somehow justified as jewelry material.
    Also, these percentages are for rough. In the gem-quality category,
    finished goods will wind up closer to 12 percent, due to losses in
    cutting. 

>       What is a jewelry grade diamond? 

    Not so long ago, that was a supremely difficult question to answer -
    it would have been an absolutely subjective matter. But with today's
    technologies, the answer is: They all are. In the past, there was a
    lot of brown and black 'bort' that would have gone on to become
    industrial grade abrasive. Now, black bort is used as high end
    jewelry. Brown diamonds have been given names like 'champagne' and
    'cognac.' Many are now irradiated and/or HPHT enhanced to fancy
    colors like blue and green. With the advent of lasers,
    difficult-to-cut rough such as carbonado (a typically black,
    somewhat aggregate form of diamond that can't be polished by
    lapidaries) may now be fashioned in certain ways. Macles are also
    easier to work with due to lasers. 

    By traditional view, some of the above doesn't qualify as 'jewelry
    grade' diamond, but there are many high end designers who are using
    non-traditional bort to excellent effect. Does the designer who
    intersperses black diamonds in a pleasing pattern among colorless
    diamonds in platinum regard it as jewelry grade? Probably only the
    ones who consider themselves 'ottists.' 

James in SoFl

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