Jan 162011

Admin: Renee Newman is a Guest Author for the AIJV.
Here, Renee comments on the need to consider transparency before making ill-informed quotes on value.

On January 11th, National Jeweler, posted a story entitled “Precious gems found in Detroit fish tank.”

An old fish tank there was found to be full of faceted and unfaceted gems. A gemologist told police that three of the stones alone could be worth more than $100,000.

Photo 1. Transparent green zoisite (5.45 cts) from Pala Gems International

A video on clickondetroit shows an emerald from the tank gravel appraised at $35,000 and a so-called Kashmir sapphire appraised at $40,000-$50,000.  It’s not surprising that they ended up in a fish tank; they look semi-opaque.  Emeralds, sapphires and rubies with no transparency normally have little value, which explains why the starting auction bid for these stones is $5.

On the other hand, stones such as transparent green zoisite can be as expensive as tanzanite (the trade name for blue to purple zoisite). In order to differentiate transparent from non-transparent green zoisites, dealers call the transparent varieties green tanzanites. An example of green tanzanite is shown in photo 1.  Compare it to the green zoisite pedestal in photo 2. The value of the ruby frog and green zoisite is primarily determined by the artistic value of the carving, not by the intrinsic value of the semi-opaque ruby material and zoisite.

Photo 2. Ruby and zoisite carving

Transparency and clarity are often interconnected, but they’re not the same. A stone can be transparent like crystal, yet have a low clarity. Likewise a gem may be flawless, yet be translucent. Even though transparency can have a significant impact on price, lab documents seldom include it as a price factor. However, often on identification reports, labs list transparency in the description of the stone.

Some of the rubies, sapphires and emeralds identified as transparent, though, are not transparent. This is one of the reasons why it is important to look at gems before you buy them. Don’t neglect to judge their transparency; if you do, you could end up believing that a $5 stone could be worth $50,000.

You can learn more about transparency and other value factors in my book Exotic Gems, Volume 1: How to Identify and Buy Tanzanite, Ammolite, Rhodochrosite, Zultanite, Sunstone, Moonstone & other Feldspars.

Renée Newman
Los Angeles, USA.  January 2011


Image credits:
Transparent green zoisite  by Wimon Manorotkul
Ruby and zoisite carving by  Renée Newman
Video capture courtesy of ClickOnDetroit.com

Disclaimer – The AIJV blog is authored by a selection of AIJV members and guests specifically to be able present many different viewpoints on a large variety of subjects. The opinons expressed by the authors are not necessarily those of the AIJV.

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Renee Newman

Renee Newman is a professional author of gem and jewelry related publications aimed at anyone who buys gemstones or jewelry, be they a consumer or trade professional. Renee's series of books are well known for being well researched, informative and colorful. She is also a great supporter of the Independent Jewelry Appraiser and we are delighted that Renee is on our Guest Author team.

  7 Responses to “Fish-tank “Gems” and the Neglected Price Factor”

  1. Thanks for that Renee. I would love to know what these stones actually sold for. I suspect it will bring a whole new meaning the gemmologist’s reference to “priceless”

    • The blue sapphire sold for $39,760, The large emerald sold for $18,000 then was reauctioned at a nicer auction house and sold for $108,000. The smaller oval emerald sold for $22,0000. I was an employe of the auction house when these were found and sold. The whole tank grossed over 7 figures.

  2. Rene,

    Great to see your emphasis on transparency. In my own book, Secrets Of The Gem Trade, The Connoisseur’s Guide…, I made the point that transparency or as gemologists say, diaphanity is one of the four Cs of connoisseurship.

    This concept is embodied in the old term “water” as in “gem of the finest water or first water”, a term used by Jean Baptiste Tavernier, Jeffries and a number of other authors up until the end of the 19th Century. Water, as Shipley correctly defines it; was the combination of color and transparency which was considered the primary factor in the evaluation of gems and diamonds in former times.


  3. Richard

    It makes you wonder, then, why Shipley decided to leave transparency out of the GIA diamond grading system.

  4. I came across your article regarding the fish tank gemstones. I just wanted you to know the gemologist that was called in is a world renowned gemstone broker. Did you know price was factored based on the face that the stones were faceted in the 1780-1800 time frame? Or that none of the stones were treated in any manner? Furthermore the stones were of the solid crystal species of gemstone advertised. This means that there was no host rock dyed and faceted into the large gemstones such as nearly every opaque precious gemstone listed for sale over 100 carats in today’s market. I worked on the staff at the auction block. I was there when the stones were found, When Derek was called in, when Derek literally brought a van full of testing equipment (even portable xray machines and ultrasound machines. I also watched the “$5” gemstones sell for $18,000 – $22,000 – $7,000 – etc…. Your article makes you look uninformed in the jewelry industry, and especially in the antique jewelry industry. There is something called heritage. Your article was read allowed at the auction block while over 100 people laughed at your ignorance since over $180,000 of gemstones sold out of that lot.

    • Dear John,
      If the fish-tank gemstones were so valuable, could you explain why the “clickondetroit” video said the starting bid was $5? Legitimate auction houses do not start bids on valuable stones at such a low price. I didn’t state a specific value for those stones. I said that $5 was the starting bid. However, I have seen semi-opaque “sapphires” and “emeralds” resembling those in the picture selling for $5/ct and even less at gem shows.

      What are the names of the auction houses that sold those fish-tank stones for thousands of dollars?

      Why didn’t the “clickondetroit” article say the stones were faceted between 1780 and 1800? What proof do you have that they were faceted at that time?

      What proof do you have that the socalled “Kashmir” sapphire was from Kashmir. Which lab issued the origin report?

      The fact that some people may have paid thousands of dollars for the fish-tank stones does not make them valuable; the question is did they pay a fair price or did they get ripped off with the sellers laughing all the way to the bank? It doesn’t matter either whether an emerald is treated or not if it is semi-opaque and of poor quality—it is still a low-grade emerald. I’d rather spend $180,000 on attractive gem-grade gems. If I advised consumers to blow thousands of dollars on semi-opaque low grade emeralds and sapphires, I would be considered an incompetent and even unethical author and gemologist.

      Renée Newman

  5. Another point I would consider is insurance! I would imagine, at the prices paid for this gem material, that the new owners would want insurance coverage for loss!
    Could be huge problems when a claim is made. At what price can the insurance company source this material of equal quality? Probably around 5- $10 ct as stated above.

    Rob Mooney FGA, FGAA, RGA.

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