[Richard W. Wise]

All,

Had an interesting conversation with a European pearl dealer about figuring the price of natural pearls. He showed me how to convert carats to grains and figure the wholesale value of an individual pearl or strand. Stands have to be figured one pearl at a time He called this calculation the "one time". I have also heard it called the 'base". The base is then multiplied times the current wholesale price

This method goes back beyond the 17th Century, Tavernier talks about it. This dealer still uses it. Anyone have any comments?

By the way just did part I of a new GemWise blog post on the 2008 Las Vegas Shows. Follow the link below.

[jshepherd]

Very interesting to hear that it is still in use. What was the quality factor he used as a multiplier? Did he use Tavernier's 0.5 to 30?

[Richard W. Wise]

No he used a simpler multiplier. That is, it went from poor, fair, nice, and fine. Used the basic value criteria, luster, shape, surface... and had a three dollar range in each category so I guess you could say 12 steps.

RW

[Richard W. Wise]

All,

Ok its a little clearer now, The factor is called "one time the weight" to which the other four grading factors; surface, lustre, shape, orient are included in a multiplier that Tavernier said was between .05-30 though 25 seems to be the highest multiplier historically used.

[jshepherd]

Going back to base price ... I found something interesting in Kunz today. It is about Tavernier's Rule. Kunz claims that Tavernier was not the originator of the rule that is applied to both gemstones and pearls, but that the rule could be traced back to David Jeffries who published a treatise on diamonds and pearls in 1750-1753, and again back to Anselmus de Boot in his treatise on precious stones from 1609.

Apparently that base price or "one time" has a long, long history.

Pg. 330-331

[jerin]

Very interesting!

[New Zealand Natural Pearl]

Interesting comments on Natural Pearl Appraisals.
Do you consider "one time the weight" grading should
apply to all natural pearls i.e. conch,abalone.
Our abalone conicals we grade on an individual basis.
Example long cone, against short cone. What is the most desirable shape?
What is the point of converting a metric measurement to an
imperial one? i.e. carat to grain as gemstones are always weighed
in carat.

[jerin]

Hi New Zealand Natural Pearl
and thanks for posting the photos. Lovely earrings and on the last picture I have just to comment on the first one. It looks lika ladies slipper to me and should be great as a pendant. The second one is beautiful too in its shape and the last one has beautiful colours as well. No idea though as how to appraise such pearls. It´s just a pity that they are so expensive and that always are going to be collectors items rather than something for our purses, even if we most certainly would "promote" these lovely pearls from New Zealand.

[Richard W. Wise]

New Zealand,

The "one time the weight" was developed for natural oriental pearls during a time when there were a fair amount of them coming into the market, but it is mathematical so one would think, convertible. Trick is to get an accurate set of multipliers which are really the trade prices for pearls of a certain quality.

The market has now revived but is very thin. Very few people understand natural pearls so big prices but few buyers. Fine gems, particularly large untreated gems of all kinds are currently going up in a frenzy of market activity. The spate of record breaking auction prices reflects a real run up in prices. See my latest posts to my blog: GemWise. www.gemwiseblogspotcom.blogspot.com